Let's go to the movies while I show you how to work the Crochet Cast-On.
The Crochet cast-on is wonderful for several reasons, all of which I know I have mentioned here before. It makes a great cast-on when you are knitting a project that will have all 4 edges visible. Because it matches the classic bind-off, if you also work a slipped stitch edge of both side edges, you will finish with a result that has all four edges matching. I also like to use it when I am going to leave the cast-on edge plain without adding any finishing later, or when I am going to add a finish to the edge later, but haven't yet decided what I'll do (it's very easy to do a crochet edging from later).
It also makes a perfect provisional cast-on. Provisional cast-ons are for those times when you will want to come back later and knit from your cast-on edge in the other direction. I've worked a couple of shawl patterns where the pattern starts at the center of the shawl, and is knitted from the center to the outer edge. After doing this, you then pick up sts from the provisional cast-on, and repeat the pattern to knit the remaining end. Or, as I showed you recently, when I wanted to make a smoother bottom edge to the 'Flow' pattern by Norah Gaughan.
You'll want a set of knitting needles, a crochet hook one size smaller than your needles, and yarn that suits your needle size.