It's free and it will tell you everything you ever wanted to know about epoxy. Second, don't use polyester resin, use the other kind whose name escapes me at this time. Polyester resins are not as structurally strong as the other kind and also, from what I have heard and read, are harder to get a decent finish with. Also, the fiberglass cloth you are likely to find in Home Depot along side the polyester resin is probably way too heavy for your needs.
Heavier cloth is harder to fill smooth and weighs a lot.
Remember that in fiberglassing like this, most of the strength of the structure comes not from the cloth but from the epoxy itself. The cloth just provides something for the epoxy to conform to hold its shape. Third, don't try to get a glass smooth finish with the resin alone. You should mix the resin with various fillers depending what you're doing with it. After you've applied the cloth, you want to thicken the epoxy so that it fills in the weave of the cloth quickly.