I did my sons taxes and sent them and then a week later he brought over his other w2's. I don't know what to do now that I have already filed his taxes. Is there a form to correct my mistake, or do I file the new w2 alone?? Thanks for your help:)

You need to amend the filed return using Form 1040X.

If you used tax software, this should not be too difficult.

If not, go get help from a tax pro.