Can't give a blow job

Okay so my boyfriend and I have been dating for a while now and we've had sex. Recently he's been giving me oral more offten than usual and I want to do the same for him. He knows I don't feel comfortable with the idea of it and he'

s not forcing me to give him one but I want to. I just can't get passed the part where his d*ck would be in my mouth but also how do you give one? Tips please!