How do I add a corrected W2

I need to correct EI N but instructions are lacking

Yes, if you have not filed the return yet, go back and just edit to enter the information from the corrected W-2c and be sure to check that box stating it's a Corrected W-2. 

And if you need to get back to the W-2 section, use these steps:

• Log into your return by clicking orange Take me to my return button
• Type W2 in the Search box in the top right
• Click the jump to W2 link in the search results and this should take you to the Here's your W-2 info screen if you already entered it. 
• Just click Edit next to the W-2 listed there and correct all information on next screen
• Continue through until you get to the Do any of these uncommon situations apply to this W-2? screen and check the box next to Corrected W-2 - I got a corrected W-2 from xxx. 

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