Go to the Approved List and tap the "+" in the top left corner. Key in the number using the keypad.
Or add a number from the Lookup tab by swiping the number right and choosing 'Approve'. You can also add a number to the Approved List on the number details screen of a looked up number.
Please allow up to 30 minutes for any changes to take affect on your iPhone.
Please note the Approved List feature is only available to TPS Protect subscribed users.