...
Start by creating a folder called "tokens" and place all of your tokens within it. Tokens should be 100px by 100px for human sized or smaller tokens, and 200px by 200px for anything larger than human. All tokens should be optimized PNGs (ScriptPNG works great)Please refer to the Developer Guide - Product Guidelines for recommended file types and resolutions.
Next create a 300px wide optimized PNG of the cover image or a representative image name it "thumbnail.png". This will be used by Fantasy Grounds to represent the token pack in the module and token windows.
...