How do you know when you are gay and my family is really against gay people i havent told them about my thought yet what do i do?

It is not wrong, or bad to be gay.

Through out history their has been gay, and bisexuality. It is just society that has put gays and bisexuals down. Remember, to think for yourself and to not live by other peoples principles. Create your own principles. To answer your first question... you just know. You have to think, and experiment with you emotions and think of what you like.