How do I make this banner into a link?

I didn't design my site, hence my ignorance here, but on the site:

http://www.wiistockcheckers.com/

I have a graphical banner at the very top. As I'm now creating pages with the same banner, I want to make it so that when someone clicks anywhere on the banner it goes back to the main site index.

How do I do this?

Thanks

 

<a href="put the index link here">put the banner code here</a>

i think that should work

 

This should work.

 

Many thanks, I'll give it a go later.

 

<a href="yourlink">Banner</a>

 

Thanks all, that worked a treat.