Define your logo
From the Modules menu, hit the Preferences link. Then scroll down the page and hit the Attached Logo linkOption 1
If your logo is already published on the web, enter its URL in the Src box. To find out this URL, go a page containing the logo. Now move your mouse over the logo and right click (Windows) or Control-click (Macintosh) to pull down the contextual menu. The menu varies from browser to browser, but you will find an option to open the image in its own window. Doing so allows you to copy the resulting URL (web address) for the graphic and paste it into the Src field.
Option 2
If you have the logo on disk, you can use the Browse button to select and upload it to Caliban.
If you want your logo to act as a clickable link (for instance to go to another web site), then enter the URL of the web page in the Link field.