Then you need to amend your first original return to add it.
How to amend an Online return   https://ttlc.intuit.com/replies/7276596

Yes.  You can efile until mid October.  Did you already file or were you waiting for it?  If you have a tax due the payment was due by April 15.  If you pay late they may sendbyou a bill for some interest.  If you are getting a refund there is no penalty for filing late.

I filed 2 but just got my w2 for last job in mail. I want to file it also/ in addition.