1) Go to
http://imageshack.us/
2) Pick the file(s) you want to upload and set 'Image Resize' to 'Do not resize'.
3) Click on upload and wait.
4) You'll be redirected to a new page with several links to the same image. The one you want is the Direct Link (example:
http://img718.imageshack.us/img718/3992/trollfaced.jpg).
5) If you want to insert an image in your post like this
, then look at the Bold, Italic and Underline options at the top of your message box. Hover over the other options to the right until you get 'Insert Image'. Click on it and simply paste the link, and it'll put in
tags around it. This can be done manually, which I personally prefer.
6) You can also insert images as links like
THIS. Just right of the Insert Image option is the Insert Link one, click on it, paste and click OK. Done.
The rest, such as resizing and cropping should be pretty straightforward, but if you still need help, just ask. I use Photoshop to resize, but I'm sure there's plenty of other websites out there that offers similar online services.
Done at the top of my head, sorry I can't put images on every step.