You should be receiving a 1099-R from the administrator of the 401(k) plan (I assume that this is what you meant). Yes, you will have to enter the 1099-R in the Retirement section of your Wages & Income to report the income and pay any taxes due.
If you did cash the 401(k) out in 2016, don't file your return until you have this 1099-R. Hassle the administrator if you have to. If you file your return now, you'll just have to amend your return when the 1099-R eventually comes in. It's better to wait until you have it and then file.