The crafting system is very simple. You pick a profession to get crafting points in. Those points add up to your 'level' in it. When you craft, certian things have a DC. You roll your crafting skill rank+ d20 to see if you either get the DC, or go above it. If not, you fail the crafting check.
You need to gather materials to craft. These can be found by buying from other players, or going out and buying them yourself. Some of the professions can make placeables, that you can move around to any point in the module you desire. These are called fixtures. These range from wood working benches, to pots of flowers.
To see what you can make, just use a Book of Trade item, or placeable. Through there you can see the materials required for every craftable item. From there is where you also upgrade your trade skill rank, you get 2 points for ever level.