After you file

You will have to file an amended return if your original return is accepted by the IRS, as you are to include all of your income when filing your tax return.

For now, your only option is to wait and see if your return is accepted by the IRS.  

If the return ends up being rejected by the IRS, then you will have an opportunity to make the corrections (add the additional W-2) you want to your tax return.

If your return is accepted by the IRS, then you must file an amended return to correct the error.  Below is a link with more information on filing an amended return.  This link will be updated for steps to amend 2018 returns later in January as the amended tax return form (Form 1040X) is not available in the software yet.  And note that amended returns must be mailed as they cannot be e-filed.