Download a Form 1 from the ATF and send that in to the address on the paper in duplicate (two copies) along with a certificate of compliance (5330.20). A GREAT video that tells you how to fill out said Form 1 can be found in the blog tab at silencedamerica.com
If you use a trust you have to include a copy of that. If it's a CLEO sign off you have to do all that paperwork instead of the trust.
Slip in the $200.00 check and wait 6 months.
Hope that helps.