Oh resin's so much fun!!
But I know it can be a bit overwhelming at first.
You'll most likely want to buy clear resin and then add drops of liquid coloring (sold next to the resin) to tint or color it (they have transparent and opaque). But you can always mix in other things to color it - experiment! 
We featured a beginner's article about different ways to use resin in the January 2007 issue of Art Jewelry. Its techniques included a picture on a charm under a layer of resin, a 2-sided window of resin within a frame, and a layered montage built up with resin.
The article's entitled 3 Ways to Use 2-part Epoxy Resin. You can purchase it for download, here.
Have fun,
~Addie~