When you finished entering your W-2, you came back to a screen that showed your entry ad had a button saying Add Another. You needed to click that and choose your wife as the perso whose W-2 you were going to enter.
Now, just click on Federal Taxes, wages and income, W-2s. You'll come to eh same little summary showing your W-2, choose add another below and make sure you choose it's for your wife. I'm assuming you have already been all the way through the Personal Info section to enter your wife's information and choose your filing status of Married Joint.