The application form used to apply for advance parole is Form I-131 (Application for Travel Document).  There is no fee to apply for advance parole if you are waiting for your immigration status to be adjusted.  When you complete Form I-131 you will need to attach 2 passport sized photos and a note explaining:

1. that you are the spouse of a U.S. citizen and awaiting adjusted status,

2. why you want to travel outside of the United States, and

3. when and where you plan to travel. 

The fastest way to apply for advance parole is to include a completed Form I-131 with your I-485 (Application to Adjust Status).  If you include Form I-131 when you file form I-485, follow the instructions for filing Form I-485.

If you have already filed your I-485, you must wait to file Form I-131 until after you receive Form I-797C from U.S. Customs and Immigration Services (USCIS).  I-797C is a receipt informing you that your I-485 (Application to Adjust Status) is under review.  Attach a copy of Form I-797C to your I-131 Application for Travel Document.  Depending on the first three letters of your I-797C receipt number, submit Form I-131 to the USCIS Lockbox in Dallas, Chicago, or Pheonix.  Check with the USCIS website for the latest information on where to file.  Complete instructions for filling out the I-131 may be found online at http://www.uscis.gov/files/form/i-131instr.pdf

If you need your advance parole as soon as possible, call the USCIS Customer Service Center at 1-800-375-5283 for advice or to make an appointment at the nearest USCIS field office and explain your situation.