You just call the agencies and it's all done via an automatic menu. The phone numbers are available online. IIRC the names are equifax, experian, and I can't remember the 3rd (Transunion?).
I did it when my wallet was stolen. Basically, anytime somebody tries to take out a loan using your name the institution offering the loan has to call you at your home phone to make sure it is really you. Well worth doing imo.
- Equifax 1-800-685-1111
- TransUnion - 800-916-8800
- Experian - 888-397-3742