How to Add pictures
First setup what you want to take a picture of, by making sure the game quality is where you want it (In-game:Options) and also that it is the size you want it at.
When you are ready to take a picture press on your keyboard. Next open up Paint (For PC:Start->All Programs->Accessories) or a similar program and press + to paste the "Printed Screen" (copied to clipboard when you pressed the button).
Go to File->Save As... and save it as the proper name because it will get confusing later if you don't.
Next you want to go to any MQWiki page and click Upload file on the bottom left in the toolbox. Browse, open the file, and upload the file. This will automatically redirect you to your uploaded file page. Here you can edit your file page to include the actual page the file will be posted in.
Your link will be in RED because is has not been written yet.
Now you can click your newly created page link to direct you to the actual page where you can edit and enter the proper code for the category you captured the image for.
From here you should follow the Help:Editing guides for entering code.