Images are posted a little differently on GTX0. It's done this way to conserve loading time and keep the table that handles replies from stretching.
The original post can have an image shown as is. To add one, click "Edit Mode" and then right above the post title, click "Image". A popup will appear. Put in the link of the image (it must be on an external website), and viola!
In a reply:
Use the syntax where "whatever" is the link to an external image. A link called "Show Image" will appear. Click it, and if you are using a modern browser, the image will show up on the upper-right of your screen.
You can also give an image a name with the following BBCode syntax:
X = the image's location
Y = what you want to replace "Show Image" with.
When the box opens, click "Close Image" or double-click the image to close it. You can also click "resize" in the upper-right corner to resize the image if it is too big.
Internet explorer doesn't currently support this feature, but we are working hard to give IE users something similar. In the meantime, scroll to the very top of the page to see the image.