"Java Script" question

Howdy folks.....I have a GREAT Domain Name that draws homeowners looking for "Roofers" in my area.

Instead of having ONE "Roofer" pay $1,000 a month to be the only "Roofer" on the Page....I'd like to place a Column with 4 Squares ....1 on top of the other so that the Squares rotate....Top goes to bottom and the other Squares move up one space....with each visitor to the Page....so that ALL 4 Squares get Equal Time at the TOP.....so that with this Rotation I could charge $250/mo for each Square.

I KNOW there's a Java-Script that can do this BUT.....anyone know How or Where I can find it?

Thanks much,
Don Alm