YouTube has some great videos on free motion quilting. Depending on which brand of machine you use, that machine's website should also have some videos on how to use particular accessories, or the dealer for that brand should be happy to show you.
I feel for you - the first time I attached my quilting foot and it started making a clunk-clunk-clunk every time it hopped up and down I thought I was doomed. You'll be just fine - do a couple of practice sandwiches and before you know it you'll have an entire quilt done.