This is simple instructions on how to edit the wiki's main page.
1. Click the edit section at mainpage. When the editing window open, look for the templates menu.
2. Click on the template tab and chose the option Show list of used templates
A small window will appear and lists all the templates used in the mainpage.
Here example what you get:
Template:About (Edit) Template:Categories (Edit) Template:Helpout(Edit) etc.etc...
Just click the edit option and it will open to a new window. Then just proceed with the editing ;-)
This is the simple and basic editing of the mainpage design.
Any question just message me.
Have fun editing!