I have a best frend for3 years he is the one I want to have sex with
but I am afraid I have ben looking at some videos and they scare me
they are doing it to fast and hard he is taller and biger than me
so what should I do

Some women like it fast and hard, but most do not. What you are seeing is not an accurate portrayal of the way most people have sex. But you can have whatever type of sex you want. You run the show. If you want it soft and slow, tell him. If you want it fast and hard, tell him. If you want to try both, tell him. But whatever you do, DO NOT every continue having sex with someone who won't honor your desires and your boundaries. If he is not doing it the way you want him to, tell him. He has no way of knowing otherwise. He's probably seen those same porno tapes and thinks that's the way he's SUPPPOSED to do it. Communication is key, and remember, sex should never be painful. It should be extremely pleasurable. Have fun!

I don't know your culture, you write with a foreign acsent though. You have to remember Pron videos are a show. Some of the things they do are beyond the scope of normal sex. So don't expect to have sex for hours on end the first time. Or expect your boyfriend to last for hours until you have ten orgasms. Ain't gonna happen. Now to the problem of pain and size
Most men want to get maximum depth. It's a man thing. If he has a large penis he can hurt you, ruin the mood, and possibly turn you off to sex completely. I suggest you take control. Allow him to enter you then close your legs so his are on the outside of yours. That way he can't bottom out in your vagina. At the same time he will be stimulating your clit and his penis will also get maximum stimulation. This might get him off too quick but if he's not a macho clod he will continue (with a little rest) until you are satisfied.
Hope this helped
Old Jim