You will not being using either of those since Code C is related to Life Insurance and Code DD is related to Cost of employer sponsored Health Coverage. Both of those will not be used on this form.
The form is basically trying to determine the amount of HSA Contributions you made in 2021. If you made any HSA contributions through your employer and payroll, then it would be listed on Box 12 with a code W. So if your Form W-2 has a code W on Box 12, then you would enter it in the beginning where you entered your W-2 Information and it will automatically flow in this section since you cannot manually enter it here. However, if there were any contributions which you personally made which were not through your payroll, then you can add those in the box which states "Any contributions you personally made".
