6
To set a link, use the following HTML:
<a href="URLwhereToLinkTo">YOURLINKTEXTa>
After you made the changes to the appropriate file, and uploaded it, go to Sys Admin -> Modules.
You should now see a table with all installed modules. To the right there are two images, which work as buttons. Hovering over them lets an explanation text appear. The left button/image is the one to update the module.
As you have manipulated a file from the system module, click the update button of the system module. This will (should

) make your changes effective.
HTH