To provide a nice graphical user interface, as well as prettifying the wiki and the website, having some buttons and icons would be nice.
This task is about gathering and writing down what sizes are useful, and what kinds of icons are needed (and what they could be used for).

For this, you have to research what icons a current desktop environment uses (there are icons in /usr/share/icons) and then specify what motives are useful. You do not have to say there should be an icon for "file browser", but an icon for "a cupboard holding folders". The icons should stay generic.