I thought that you had to be a level two member, meaning that you have participated in the community a bit. Also, I think that you can post links provided that they are not affiliate links or promotional.
there are no signatures that are added automatically. you can put a relevant link either in the body of the answer, or in the "reference" box. and also if you're level 1, the link won't be clickable. only after you become level 2 get a chance just to click and get to the resource.