We can host the images in sites that offer this services for free. In this example I'm going to use: http://www.imageshack.us
So go to http://www.imageshack.us and you will find something like this:

Click the BROWSE button and the Browse Window will pop-up.

Select the file you want to upload and click Select. Then Click UPLOAD NOW!

Allow the system to upload the file...
Imagehack will show you the following options:

Select the Forum Thumbnail code, Copy it (PC: Ctrl+C; Mac: Command+C) and Paste it (PC: Ctrl+V; Command+V) at the Alopecia Forum...
And that's it!