About mouseover effects

[naranjadulce2002]

Gentlemen:

My question might seem to all of you quite odd but I am just an amateur.
I have this website for a games league in Yahoo and I am posting some trophies for our members. I have seen in some internet pages that when one puts the mouse over a graphic it show a tag with information about that graphic and thats what I would like to learn to do. Your promptest help will be most appreciated.

[Twey]

<img src="image.jpg" title="A Trophy"/>