The short answer is, you can’t register for the gallery.
If you want to post pics in threads you can host the pics externally and link to them, or you can send them to me (or Primz) and I can put them in the gallery for you.
That’s my understanding so if I’m wrong I expect Primz will be correcting me soon.
To host the pics you would have to either put them in some webspace provided by your ISP or maybe some other service like flickr.com.
Or, just send me the pics and I’ll put them in the gallery - which is probably a better way. Otherwise, if something happens to the hosting, or you chagne ISPs or something, then the pics will disappear from your posts.