First, they send a letter to the three major bureaus (Transunion, Equifax and Experian), stating your right to your credit report under (FCRA) § 1681g.
You can do this yourself using the following template or on the free websites provided by the bureaus.
Download File:
View On Google Docs https://docs.google.com/document/d/1GwO3Hxr4Z2-Gfb3AcWFDioXMJBKKJpEWFn1GY1tm-Oc/edit?usp=sharing