A siggy and Avi shop is where someone can create a thread and in it the make siggys(Signatures) and avvies(avitars) for other users to request!
to use a siggy or avi go to your profile by clicking your name and and looking to the left and clicking avitar or signature
Signature: for a signature you must: 1.)Save the picture (you must otherwise after about a day it doesn't show up!) 2.)copy the picture from the "post" or the "web" 3.)paste it under signature!
Avitar: 1.)save picture 2.)go to avitar (on your profile on the left) 3.)click "Upload avitar" 4.)click "browse" 5.)chose the picture from your saved pictures 6.)click the picture you want after it's done uploading (it's under Avitar in your profile!) 7.)click "select Avitar"