Note: There are a zillion different ways of doing this. In my experience imgur is much better the photobucket or other hosting providers, and doesn't screw with your pictures, or surround them with garbage.
This post is intented to help users who dont' know how to upload pictures, or want to do so using imgur and don't know how. This way I can just link people to this post.
1. Open up a browser window to http://imgur.com
2. Select 'upload images' as below:
3. Either drag and drop the pictures on, or select 'files from my computer' and select them.
4. Push "Start Upload"
5. Wait for the upload to finish.
6. Once you are done, you will see this screen:
7. Select "Large thumbnail" (huge thumbnail is a paid account option - you won't see this)
8. Press the button under "Linked BBCode" - this will put the forum code in your cut/paste bufffer
9. Go to the post you're writing, press ctrl-v on windows or, command-v on mac.
10. POST - it will look like this one does, and when people click on the photo, they will get the full size one.