You will need to file an amendment of your tax return to add the W-2s.  If you have already e-filed or mailed in your return, you would need to wait until the return is accepted, and the tax due is paid or the refund status is "Refund Sent" before you can amend their return.

Here is a TurboTax FAQ for amending your tax return:

https://ttlc.intuit.com/replies/3288565