As @DoninGA mentioned, all of your income goes on one tax return. If you've already filed without including all of your W-2s, you will need to amend your return when the amendment forms are ready.
I suggest waiting until your first return has been completely processed and you've received your refund before filing an amendment. Once you've received your initial refund, follow the steps in this help article to amend your return to include the rest of your income.
