This link should help
http://www.specktra.net/forum/showthread.php?t=23166
Also just click on Go Advanced, click the little icon that looks like mountains and put the URL into there.
If you don't see that mountain Icon when you click Go advanced (down by Post quick reply) Do the following
Go to your User CP, Click on Edit Options, now scroll down to Miscellaneous Options it is the last box, See where it says Message Editor Interface you probably have it set on Basic editor, switch it to Standard Editor and click Save changes.
Specktra offers you a gallery with unlimited space. Also your pics can not be hotlinked from specktra so it offers you added protection.
The Gallery is located along the same line as User CP up at the top.
When uploading pics (other than swatch pics) please choose member album or an option under member album when uploading.