To create a Mailing List using a file (CSV, Tab-Delimited) as the source, click the New List button
at the top of the Mailing List Manager. Give your new Mailing List a name (required) and description (optional), and click Next to continue.
You will then be brought to the list of sources for your Mailing List:

Select Enter Data Manually from the list, and click Next to continue.
You will be given the contact data entry form. Enter all necessary data for a single contact by using the corresponding fields (shown below). Only First Name is required; all other fields are optional.
When you have finished entering a contact's information, and you would like to save this contact to your Mailing List, click the Save Contact button at the bottom of the menu. Once you click this Save Contact button, all information you have entered will be saved and then cleared from the fields. You will also see the No. of New Contacts Created at the bottom-left of the menu increase by one.
Repeat this process for every contact you wish to save to your Mailing List. Enter a contact's data using the given fields, and click Save Contact to save and clear the fields.
Once you have finished entering and saving all of your contacts, click the Finish button to finish and return to the Mailing Lists Manager.
There may be data you wish to enter for the contacts in your Mailing List that does not have a corresponding field by default. If this is a case, you can enter a Custom Field to store this information. To add a custom field, click the Add Custom Field button
at the top of the contact data entry menu. This will bring up a new window:
Enter a name for your Custom Field, and click OK to add the Custom Field to your Mailing List. You will now see the newly added Custom Field added to the contact data entry menu:

You can now enter data into this Custom Field as well.
To rename a Custom Field, click the Rename Custom Field button
at the top of the contact data entry menu. This will bring up a new window:
Choose the Custom Field you wish to rename by using the drop-down menu. Then, enter the new name for this Custom Field. Click OK to rename the Custom Field with the new name you have entered. You will now see the renamed Custom Field in the contact data entry menu.

To delete a Custom Field, click the Delete Custom Field button
at the top of the contact data entry menu. This will bring up a new window:

Choose the Custom Field you wish to rename by using the drop-down menu. Click OK to delete the selected Custom Field. You will now see that the Custom Field has been deleted from the contact data entry menu.