Pacchai_Picchai,
FBI clearence for Canadian immigration is different. Here's the procedures:
1. Pls go to the local Police Station and ask for FBI Fingerprint Card. Police officer will take your finger print on the card. Probably, they will charge $5 for that.
2. Send this card with Certified check/money order of $18 payable to US Treasury to:
FBI, Criminal Justice Information Services Division (CJIS Division)
SCU, Mod D-2
1000 Custer Hollow Road
Clarksburg, WV 26306
A copy of the letter should be attached with this that you have received from Canadian Consular office. You will receive FBI check results within 6-8 weeks.
This information is about two yrs old and you can get updated information from their website. I got my Canadian PR two yrs ago.