Go to http://www.immihelp.com/visitor-visa/sponsor-documents.html.
Print out two copies of Form I-134 (Affidavit of Support Form).
Fill out one of the I-134 forms for each of your parents.
Collect a letter from your employer stating the duration and nature of your employment and your salary; three recent pay stubs; a letter from your bank stating when your account was opened, the total amount deposited in the last year, your present balance and your average balance in the last year; bank statements from the past six months; a letter to the consulate stating you will take care of expenses while your parents are here; a letter of invitation stating you can accommodate them; income tax documents from the last three years; proof of U.S. citizenship; proof of legal status of siblings (if you have them); and if you are sponsoring your in-laws you will need photocopies of all pages (including blank pages) of your spouse's passport and a photocopy of your marriage certificate.
Send the I-134 forms and all of your supporting documents to the required consulate.
