sex positions

Do you ladies (and gentlemen) have any suggestions on learning how to do different positions. Up until now, when having sex the man always did everything. I guess some would say I was lazy (even though they never required or asked). Tonight my current boyfriend asked me to do a few things that I was unable to do (riding and 'throwing it back'). At my age you'd think I'd know these things by now. I was so embarrassed. I apologized, especially since we didn't finish. He said no need to apologize, that it was ok. I left his house and went home. I don't know what to do. Help!