Open Question: amend tax return due to status change?

Hi, my brother filed his taxes as single for the 2009 year. He got married in December 09. He did not realize he could have filed as married and gotten better returns until I told him so. How can he file an amended tax return? Is this ok to do or will it raise some sort of a flag? He also needs to apply for her ITIN since she doesn't have an ssn yet. Thanks.