Long and short, two options:
1) Take the web address (URL) of the picture and wrap it in IMG tags, like:
[img] link-to-picture [/img]
(Note: Remove the spaces between the []s)
I normally use http://www.tinypic.com to upload my pictures and get a URL link to them.
2) Use the "Go Advanced" posting section, under the text entry area, click "Manage Attachments" and upload the pictures there. Beware: If you go back and edit your post, you may find that the pictures disappear until you re-enter the "Go Advanced" area to edit the post again to make them show up.
If neither of these two make sense, let me know. I will give you a link to a PDF I made to help people post pictures - it has step-by-step details.