You'll find out the name and contact information for your trustee when your Form 309A, the "Notice of Chapter 7 Bankruptcy Case" arrives in the mail a few days after your case is filed. If you're filing in person, the clerk may be able to tell you who your trustee is right away.
Trustee's Contact Information
Form 309A has the trustee's name, address, phone number. and email address listed in Box 5.