Welcome to the forums. As a new member you may only post new threads in the Noob Forum (
http://www.405th.com/forumdisplay.php/21-Noob-Forum). A button in the upper left corner of the forum gives you the option to post a new thread. Once you are a full member (infantryman) all forums will have this option except for the Elite Forum, as only exceptional projects are placed their based on the opinions of the site's moderators.
I highly suggest taking time to look around the different forums and reading through sticky (stickies are found at the top of the thread list in each forum), tutorial, and work progress threads to gain a good understanding of the processes and materials involved with this hobby. This will take some effort on your part but will benefit you greatly in learning how to excel in the armor-making craft. Good places to begin are with Roadkiller's reading list (
http://www.405th.com/showthread.php/30542-NOOB-reading-list) and Spitfire22V and company's all-in-one new member introduction guide (
http://www.405th.com/showthread.php/34408-All-In-One-New-Member-Introduction-Guide). Good luck with your builds.