You first save something in one of your image folders (you know how when you right click an image, you can save it?). You go to Upload File and click browse. Pick that saved image and click open. Then click the upload button and the image will be seen on the page, with the code
Image:whatyousaved.jpg
now put that in double brackets. Write it like this:
[[Image:whatyousaved.jpg|thumb|none|600px|Text comment.]]
You can change the 600px to 400px or any other size and can switch to right, left, or center in place of the none. It's complicated at first, but eventually you get the hang of it.
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