If you want to know how to do frame by frame animation, then just try this:

On frame one, draw anything you want. Press F7, draw something different.
Test your movie, there you have 2 different frames. Now, if you want to make something GOOD, then let's say draw a guy in your first frame. Press F7, and turn on onion skin (it's just under the layer names). Drag the left wall so it just overlaps the frame before your currently selected frame. Now that you see your guy again, draw him again moving to some position. I do this, and it takes a really long time, but the end result is the best you can get if you do it correctly.