my boyfriend wants me to take a hot picture of myself in a bikini for him how shude I do in the picture?
At your age...nothing provocative. No lewd poses, nothing nasty. Depending on the pose and such, it could be construed as soft core child porn. Don't need that.
If you do go through with it, though, just be yourself, have a little fun. Check out the Sports Illustrated Swimsuit edition for ideas, BUT, make sure he's not going to spread these pictures around. Unless this is what you want him to do, I'd actually advise against taking the pictures. A person can say they'll do one thing, but as teenagers, they lie...a lot. "Hey, check out my girlfriend." Now he's showing everybody. Don't need that kind of humiliation.
But tip: everything stay ON. At your age, I'd tell him no, though. He doesn't need "hot pictures" of you. And if you you, nothing less than fully clothed.
I'd advise against it, personally. Tell him he needs to wait a few years, then you'll give him the show of a lifetime. ;)
Don't do it! Simply say to him that you don't feel comfortable taking these photos for him. You never know what could happen. This may be one of your biggest regrets! Yous may eventually get into a fight (Just like any couple would) and remember, he will still have those photos of you in your bikini. And you would be hoping that he would not do anything. But he is a male, what can you expect? He will show everyone. Sorry for being a bit too straight forward, but you needed to hear it from someone before you made a big mistake that you won't be able to take back.