I received a W2 and W2c from my employer, but my W2c is mostly blank with only one correction filled in. I want to mail my tax forms. How do I do this?

Which box was corrected?

Simply attach both the original W-2 & the W-2C to the return. 

Will I need to fill in any missing details in my W2-C or will that not be necessary?

Leave it alone and send it exactly the way it looks as sent to the IRS by your employer.