To add (imbed) an image within a posting (like this one), you need to have the image located on a file sharing site. Anything like photobucket or SmugMug (what I use) can share the images.
Here is an example:
When you are typing your post, and want to add an image, select the Img tag from the options, copy or paste the image location (from SmugMug, etc) and then 'close it with the Img tag again. You have to approach this with some HTML knowledge, sorry.
Hope this helps