All you'll have to do is launch the Actor Viewer. Once in there, there will be different columns for different kinds of things.... Name, Model, Texture, Animation, Props. It looks much like a spreadsheet. Just click into a cell and hit browse and choose the proper animation, texture, or whatever you want. It's pretty darn easy. Sorry if I'm a bit vague. Just rest assured it is already created (the Actor Editor), because I've been using it for a couple of years now to piece together the units of the game.