How do I save what I've done so far and add another w2 later

[VolvoGirl]

Just exit, your return is automatically saved.  Then log back into the same account.  

https://ttlc.intuit.com/community/saving/help/can-i-save-my-return-and-come-back-later/00/25873

[rjs]

In TurboTax Online all your entries are automatically saved. You can sign out, and when you sign in again later with the same user ID all the information that you entered will be there.