Gloss will make the object shiny, Matte will make it not shiny. Well, now you have an idea where to get your paint, you need a project. While you were at the craftstore, I hope you wandered around looking at all the stuff. If you were observant, you also found the styrofoam and the balsa wood. Styrofoam is nice for making lightweight pieces from, and you can make bigger objects, I recommend using it for rocky terrain, buildings and walls.
Balsa is cheap, and useful for detail pieces, and for making fences and low walls.
Those AOL CDs are good for making hindering terrain. Just prime and paint them green, add some trees from a model railroad shop and it looks good. You can make water from plexiglass, just paint the bottom side, and it will have a depth effect. These terrain pieces will cost money, but you can slowly add them to your collection, especially if you already have the felt terrain system. The supplies and tools should be purchased as you need them.