You can add it in the blogroll there. Optionally you can add it in the sidebar by creating a text/html widget and add the html code in it. You can also add html code of your activities in it's sidebar in a manner similar to.

Go to add new link in under the Link heading in the Admin dashboard. Here you can define and name the link you can also attach it to a category. Then go to thesis options and Navigation Menu, then use the Add more links option.

I tried a few things before I got it working so I may have missed something, let me know if you have a problem.