The manual tests written as part of the hackfest are utilized for manul testing efforts throughout the cycle.
Setting up the tools
Before you begin make sure you have a launchpad profile, and your machine is setup to work with bzr and launchpad. This tutorial will make sure you are all set.
If you want to get started in advance of the fest, check out the tutorial for writing manual testcases, the style guide, the manual testcase format, the manual testcase check script and the project itself on launchpad.
Once you have a background on how tests work, you can view the specific hackfest page itself linked from the hackfest page to pick and plan the work items you wish to tackle during the hackfest.