The following help pages are available.
To insert an image, click on "File attachments" while editing a page and upload an image file from your computer. To delete an image file, click on the "delete" checkbox and save the page. There is also a "list" checkbox which controls whether or not the image will be listed at the bottom of the page; in most cases, you will want to turn this off. Images are uploaded into a single directory, as on Wikipedia.
If you have problems, your first port of call should be the forums. If that does not work, or if you wish to report a security issue, please send a message to the address webmaster at tricki dot org.