This is kind of long. I kind of knew about masturbating but got some help figuring it out.
Mom and Dad were divorced. My little brother Jeremy and I were staying with him for the summer. We had a cabin at a resort in the mountains and went up there for a long weekend with dads girlfriend (I didn't like her) and his friends Bob and Pam. I liked them. He was tall handsome and strong with a really nice body but I always sneeked looks at when I could or even his front cause he wore tight jeans and you could see the outline of his wiener it always was off to the left and straight across. And Pam had long blond hair skinny waist and I would guess 38D boobs with big nipples that were always hard. She didn't wear a bra and always wore tight clingy shirts and her boobs would always sway and Bob around. I was just starting puberty and hadn't figured out my body yet. What I now know was sexual tension was flowing electrically the whole weekend between dad and his girlfriend and Pam and Bob. I did know I loved being around them and every time I breathed in the smell of them my crotch would tingle.
The cabin had two rooms right next to each other that connected to a shared bathroom. Jeremy and I got the room with two twin beds and Pam and Bob got the other that had one big bed. Dad was in the master bedroom on the other side of the cabin. After a while of being in bed Pam and Bob went to bed and we heard them grunting and moaning and breathing heavy and squeaking. Jeremy asked what are they doing and I said having sex and we both got quiet and listened. I was squeezing my thighs together and thrusting my hips up (I hadn't figured out how to masturbate yet) I did sneak my hand up and touch my boobs though. I looked over and Jeremy was face down humping the bed he got going like a rabbit so I thought I'd give it a try but it didn't do anything for me. Then after a while things became quiet. Then I saw the light in the bathroom turn on I had left our door open on purpose and taken the bed next to the door in hopes of seeing them naked. And I saw Bobs cock as he walked in it was huge and glistening sticking straight out and kind of drooping not like Jeremy's little thing that always went straight up when it was hard. I pretended to be asleep and watched his cock wiggle and Bob around as he washed up then he went to pee. I didn't get to see that it was behind the door and then got to watch his but as he walked back. My crotch was on fire and I was too stupid to figure out how to take care of myself. I spent the rest of the night thinking about how Pam got that big thing into her.
Well the next night we were all watching a movie and Bob and Pam left in the middle of it and went to the hot tub. So Jeremy and I went out there eventually Dad stayed in making out with his girlfriend. Pam and Bob were drinking wine and we asked if we could have some they said no but let us taste it. After a while my brother dared me to take off my top and press my boobs on the window of the cabin. And I did. I felt really sexy being topless in front of them. And I came back and hopped in. I could see that Bob had his arm around Pam and was playing with her boob while staring right at mine I had pointy a cups at the time. Pam had her hand on his cock. This all was just driving me crazy. So then I dared Jeremy to take off his trunks and go put his wiener on the window which he did. Then he dared Pam to take off her suit and I did the same to Bob but they said they better not and that we should get dressed. So I put my top back on but Jeremy didn't put his trunks on. So I said you have to do truth then. And asked them how to masturbate. They explained about my lips and at the top of them was my clit and that was what I should rub and keep going even if I thought I was going to pee. Well we all eventually got out of the tub and went back in and watched another movie Pam and Bob were laying on one side of the long L shaped couch and I was on the other. He was down to just wearing a towel. Eventually everybody but Pam and Bob and me went to bed. I was pretending to be asleep and trying to catch another look at his cock under the towel when Pam sat on the floor in front of him he was rubbing her neck and Payday he spread his legs wide and his cock came out slid up onto her neck and shoulder as he worked his way down to her boobs and wound up taking her top off. Her nipples were really big compared to mine they were like the size of my pinky and I would guess about an inch long he was rolling them and twisting them. She started moaning and he said shh... don't wake her. Then she turned around and started jacking him. It was amazing, eventually she stood up and they went to their room to carry on where they left off, as I heard the bed squeaking again. I stayed out and had my first orgasm. It was wonderful.
Pam also suggested that I take a mirror and look at myself which I did. And also told me about brush handles and carrots and cucumbers and stuff which made things even better.
Pam and Bob lived on a small ranch and Pam said she would give me riding lessons. We started with her in the saddle and I hopped on back the saddle made me slide right tight up behind her and she Told me to hang on so I wrapped my arms around her and we started around the arena she said it sort of tickled and for me to move my hands up so I did and they were right under her boobs and as we bounced around the arena her heavy boobs bounced down onto my hands she had no bra on again it was kinda turning me on. Then after a while she had me take the reins and put them in my hands. She told how to hold them in and had me hold them so my hand were basically rubbing her boobs and I was getting totally wet. The sides of my thumbs were rubbing on her big nipples. Then she said OK now its time to switch and pulled my hands with the reigns back into her boobs. And after the horse stopped she leaned forward and said lean back and lifted her leg high over my head and hopped off. She adjusted the stirrups for me then climbed up on the fence and got on behind me as she slid down her heavy breasts hit my head and I felt them part and slide down the sides of my head and down to rest for a second on my shoulders until she adjusted and then I could feel the big hard nipples rubbing around on my back as we moved. She reached around and took my hands gave the horse a nudge and we were off she held my hands and put them up to where her hands were now rubbing my boobs as we went. It felt nice I was getting really turned on cause she was basically rubbing my tits. Then eventually she let me have the reigns all to myself and rested her hands around me in my lap. Her fingernail scraped on the seam of my jeans and sent an electric shock through me. She asked me if I found my Clit I told her yes that night and that I used the mirror and tried the stuff she suggested. She said good and ran her fingernail down and up the seam again which made me gasp. Then she said 'I have to go take care of something' and got off the horse and told me I could keep riding. She went inside and I'm not a lesbian but I slid my hand down my jeans and took care of myself right there and I couldn't help thinking about being with her as I did it.