I am creating a software web site and need to include screen shots.

I have created a module that shows in the left-hand column with the text "Screen shots" after the user clicks on the menu item Product, then subitem Product1.

When they click on the menu subitem, a "Custom HTML" module called "Overview" shows in the middle of the page describing the product.

I want the user to be able to click on the link "Screen shots", and replace the "Overview" module with the module showing the screen shots.

How can I do this? Thank you!