How to make a rollover button:
First you want to make a button.You want this first layer to be the the normal state of the rollover button(when the mouse is not on the button)
Here is the button im going to be using:

Now you need to make an layer that you want to be the rollover state.(when the mouse is over the button)
here is what i am going to be using:

Now you want to hide the layer that you want to be the rollover state:

Ok we are ready to switch over to imageready.
Now we need to create a rollover state:

Should looki like this after you creat a rollover state:

Now once you create the rollover state you need to unhide the rollover layer while the over state is highlighted in the webcontent box:

should look like this:

Heres my rollover button:
Previewyou can preview your button in your web browser by clicking the Intrenet explorer button on the tool palette.