1. Remember that the limbs and even a mouth that you want to move should be on it's own layer. My bug below has his legs and upper arms on their own layer and each layer is named.
Click a frame on the other side of the timeline and then shift-click all the way down or drag your mouse down to select all the frames in the layers that contain the bug.
Right-Click and Insert Frame or press F5.
Right-Click again and Create Classic Tween.
Now Stop!!!
I know you want to insert the keyframe now but don't. Go back to frame 1 and click in each layer.
Select the Transform Tool
Move the center of each body part to where it will pivot around. If you don't do this all hell will break loose later and you will have much more work to do to make your arms stay with the body as they move.
Now that you have moved the pivot point for each limb, you can now go make your keyframes in the last frame. You can do it to all of them at once by selecting all the frames and pressing F6. F6 is the shortcut for creating a keyframe.