New to Sex

So I'm new at the whole sex thing and figuring out what I like. Every time so far has been painful, and the last time I was with a guy, I tore a little bit. My boyfriend wants to know how we can make it better, and I have no idea. I know foreplay can really help with arousal- but what even is foreplay?! I want to know what things I could try to make it more comfortable for both of us, and I only know a few tips. Help a girl out?!