DNC requests and DNC lists can be uploaded in a couple different ways either either by the "Requested Do-Not-Call" disposition found in your "Contact View" tab or by adding numbers through the "Admin" tab.
To add a number during a call you would go to your Contact View tab:
Next from the Disposition Bar select Made Contact and Choose Requested Do-Not-Call as shown below.
To add numbers from a CSV file you will go to the Admin Tab
Next you will select Manage Do Not Call List
Once in the DNC upload screen you can either upload numbers individually or from a CSV file. If uploading files from a CSV file (example below) you must include the column header Phone and must have a capital P so your column header name will appear as Phone. All subsequent fields in column A will be the individual numbers in the following format (###) ###-####
Note If you are using a Mac you will need to save the file as a Windows CSV file