Making Graphics Clickable

[Phasar]

When I installed SMF I told it the name of my site and the graphic to use, which appear at the top of each page. I would like to add code to make the name and the graphic clickable back to the main site. In other words, someone clicking on the name or the graphic would be taken out of SMF and back to the main index page of the site. How can I do this, and where do I find the code that needs to be changed?

Thanks
Frank