Erm. I'm male but I imagine that female orgasms aren't all that different. The "you'll just know" bit is completely true. During sex you'll (hopefully) feel pleasure that consistently ramps up. The orgasm, however, will be an intense spasm of pleasure. As a male I experience waves of pleasure with each spurt. As a female I'm not sure if you'll feel waves or just one big lump of orgasmic bliss.
I think your best bet is to work on achieving orgasm alone. It's probably much more challenging to experience one with a partner. Once you can consistently orgasm on your own then you should worry about having one with the boyfriend. Uhm. How exactly to have one on your own is a topic best explained by a female. I find myself unable to even conceive of not having an orgasm from simple friction.
God, so atrocious in the Old Testament, so attractive in the New--the Jekyl and Hyde of sacred romance.
-Mark Twain
If people are good only because they fear punishment and hope for reward, then we are a sorry lot indeed.
-Albert Einstein