How do I upload pictures?

When I try to upload a picture, it says File extension does not match MIME type.

It means the file extensions do not match. For example, maybe your trying to upload your .jpg image as a .png. Only upload .png images unless it has to be an animated .gif. And don't change a picture's extension to .png from another image, it needs to initially be .png. Retake the picture if you must. This is to ensure discoloration does not occur. Also, this is the wrong place to post this.

If you're trying to replace a .jpg image with a .png, click 'edit' on the page that you want to change the images for, and delete the line "|PreviewExt=jpg". That'll default the page to .png format. At least, I think. Someone correct me if I'm wrong.

Also might want to check our image policy before uploading pictures.