nervous to have sex with my boyfriend advice!

I was in a serious relationship 3 years ago and we had sex. We had a nasty breakup and I was single for 3 years and now I'm dating a new guy that is pretty much the love of my live we are best friends we have been together for 4 months and want to have sex but Everytime I pull away because I havnt done it for 3 years I feel like I'm going to be bad I want to please him. He is taking it close he understands that I'm nervous but I know he wants more I want more I just don't know how to do it anymore help!