The first thing you need to do before you can contribute is you have to tell the wiki you are ready to add something. To do this, simply click on the edit button at the bottom of the page.
Once you have opened the editor (a sort of mini-word processor), you will see a menu toolbar. This menu will let you do almost any text formatting you will need. If you want more information, you can check out Wiki Syntax.
When you are done writing what you have to write, click on the save button. Voila! Your words of wisdom are included, and you have contributed toward the solution of the problem.