Simple Rollover

{Click} on the Add Button in the Behaviors Panel and the first option in the list is a Simple Rollover. Remember that you must have a Slice Object or a Hotspot selected if you want to apply one of these Behaviors

Applying a Simple Rollover to a Slice Object will swap the content of Frame 1 with that of Frame 2.   In other words, Frame 1 is the Up State and Frame 2 is the Over State. This Behavior includes both a swap image and a swap image restore function.  If you need to swap your image with the content from a frame other than Frame 2 you must pick the next item in the "Add a Behavior Menu".