On top?

How to be on top? I mean. You know what I mean! 
Every time I try, it's ridiculous, I don't know how to move and it doesn't feel good! And I feel so conscious about my body AND it's so scary seeing my boyfriend look at me while on top! 
And he told me he really wanted me to ride him... So... Help you lil' sis' out! 😳😆