Can anyone tell me how I can add screenshots to wiki articles? Specifically, where can I upload images and how do I link to them?
In the wiki you can click on "Help" -> "Mediawiki Help" and have a look about wiki-markup.
Very interestant is the following link
http://meta.wikimedia.org/wiki/Help:Reference_card .
But in short:
type something like:
[[Image:DuplicateCompiler.png|thumb|none|Duplicate Compiler]]
the first is the name the image should have on the server,
the second tells the server to create a thumbnail and show it instead of the big image (the thumb is a link to the big image),
the third: ?,
the fourth is the caption of the image.
If you put this code in the wiki it shows in red the name of the image (if it does not exist n the server).
If you now click on the red name a page opens where you can chose the image to upload.
An example how it looks like (with the above wiki-code):
http://wiki.codeblocks.org/index.php?title=Cross_Compiling_wxWidgets_Applications_on_Linux#Create_Compiler