The Code Repository is where you edit the options that will come up from the code popup (the popup menu that is accessible by rt-clicking on most of the text areas in blue).

The Code Repository features a tree to organize your code. Rt-clicking on a folder will give you options shown in the screen shot, to either add another code group, remove the current group, or add a code snippet to the group.

If you add either a code group or a code snippet it'll be added with a default name. To edit the name, double click on the group or snippet and the area on the tree will change into a text field to edit the name.

To edit a snippet, simply click on the snippet in the tree and on the right a text area will appear. In that text area, edit the text that is associated with the code snippet.

When you're done editing your code repository, the next time you rt-click on a text area, the code popup will reflect the changes you've made, including any new code groups and snippets you've added.