I'm assuming that you're talking about posting a link in VirtualDr. After clicking "Post Reply", type your message in the box. When you get to the word "here", click the box (above the message box) that says "http://" and follow the prompts. Type the work "here" in the first dialog box, and put your link in the second dialog box.
The only ones I use are "http://" and "img". To use "img", just put the link to an image in the dialog box (the image will appear in your post). The image has to be on some other site like your own web site or an image storage site (I use Ripway).
As I mentioned, the image has to be on a site where the image (not the site) has a URL - your own web site or an image storage site. Photobucket is a third example. This site (for smilies) gives you a link to various images or you can store your own images here (although, I haven't tried storing anything here so I'm not sure how it works on this site).