Basically, you can draw an image in Microsoft Paint (and/or most other paint programs.) Save the image file, then, in Game Editor, right click on your actor and click on "Add Animation." Now you can choose a name for the animation, and once you're done there, click on the "File:" button, then you can browse for your image file you created earlier.
To have an animated animation (!), either have multiple image files for each frame of the animation (and select the "Multiple Files" option), or draw each frame in one file in a vertical or horizontal manner. See the files in the Game Editor folder to see what I mean.
I hope that helped....
Oh, and welcome to the Game Editor forum!