Review the documentation of Framasoft services

You can start by picking a service you know well so that you don't need to get to know about the service and it's interface.

Otherwise, just pick one at random and use it a bit to understand what it's all about.

You can check for the following issues:

The nature of the issue and it's position

Depending on how much time and how much motivation you have left, you can try to fix the issues yourself or report them