Cool! Looks like a Tommy Iommi signature model SG.
The guitar has 2 tone knobs and 2 volume knobs. The ones to the front control the neck pick up (warmer, bassier) and the rear ones control the bridge pup (snappier, brighter... more prone to leads or distortion). The switch should allow you to toggle between bridge pup, neck pup or the middle setting is for both. The middle is fun to play around with on guitars like this because you can adjust the volume of each pick up to get nice blends between the two. The bridge pup alone will immediately make you a rock star if you're looking to make some crunchy racket.
I'm not familiar with the Crate amp, but if you want distortion there should be a gain dial or channel on there somewhere. The amp might have two channels, one for "clean" and another for "gain" or effects. If so, there should be a switch on it so you can check out both. Play around on the knobs a bit and you should get some fun tones.
Turn it up, and kick out the jams!