Using <SPAN> Tag
Mouseover text is simple to make.
When you are editing a page, click on <HTML> button on the toolbar.
What you'll want to do is enclose whatever text you'd like to have a mouseover in span tags. those look like this: <span>This is the text I want to have a mousover</span>. You can do this by either finding the text you want in the HTML editor, or by typing it yourself.