For the size of each frame, it should have the size of say:
1024x1024(likely not any higher than this, since even this size might cause the game to lag, unless you only intend on two frames with this size)
As for the texture itself, it should have a number of instances of the original, and only an even number of them. Once this is done, you need to make changes to the frames, which the game will switch between, making the animation.
Wow! simple yet complicated. Are there any tutorials on how I would use photoshop to make the animation? I understand the basics on how to make frames, but besides that........I've no idea. Also, am I supposed to change the file format when I edit it or before I put it in-game?... Once again, no idea how to do this...!