Please see sample cover letter below. Hope it help.
USCIS Address you will send to
RE: Form I-130, Petition for Alien Relative, Beneficiary Name.
To whom it may concern:
I, Petitioner Name, a citizen of the United States, would like to file a petition I-130 for my daughter/son, Beneficiary Name. Please find enclosed the following required and supporting documents:
Completed form G-1145
Check/money order for $535.00 payable to the U.S Department of Homeland Security.
Signed Form I-130, Petition for Alien Relative.
Photocopy of birth certificate of Petitioner
Photocopy of birth certificate of Beneficiary
Photocopy of proof showing relationship between Beneficiary and Petitioner
Photocopy of U.S. Passport of Petitioner
Photocopy of Certificate of Naturalization of Petitioner
Copies of documents submitted are exact photocopies of unaltered documents and we understand that we may be required to submit original documents to an Immigration or Consular officer at a later date. Please advise us if you have any further questions or concerns related to this petition.