First of all, where are you located?
If you are in the United States, then there are a few things you must do first. The very best way to get accurate information is to go here:
www.atf.gov
and contact the Compliance division. They can walk you through the proper paperwork.
Now, as for that gun in the pictures, looks like an actual MP5, with a Gemtech QD mount on the front for a suppressor. Kewl beanz--as long as it's a pre-'86 fully transferable gun.