I received a W2-C form. I received my 2021 tax return. I need to amend it. Should I update W2 form for amendment or should I upload W2-C form? How can I upload W2-C?

I cannot find any option for uploading the W2-C form. 
I found an option in which I can update the W2 form. Is that what I am looking for?
 If I update the W2 form will it be OK? Is there anything else I should do?