I uploaded a picture from my computer into Imageshack and tried to post it. when I used the tags, it came up as the blue question mark box. When I tried the method Imageshack told me to use, I got a tiny picture with the size written on it. What am I doing wrong?
Nothing, that's how Imageshack works. Click that little picture and you'll get taken to a page of the full-size picture.

If you put the url of that page (basically take out the .th part of the url they give you) in image tags, it should work how you want it to.
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If you cut down on these costs students won't learn so well, effecting the "quality"...