Items and meanings:
Enable Port Check this box to enable port mapping,
Forwarding (1): and uncheck this box to disable port mapping.
Private IP (2):  | Input the IP address of the computer on the local  | 
  | network which provides Internet service.  | 
Type (3):  | Select the type of connection, TCP or UDP. The  | 
  | value depends on the requirements of your  | 
  | application or service. If you're not sure what to use,  | 
  | select 'Both'. | 
Port Range (4):  | Enter the starting port number in the left field, and  | 
  | input the ending port number in the right field. If  | 
  | you only want to redirect a single port number, just  | 
  | enter the port number in the left field.  | 
Comment (5):  | Enter any text to describe this mapping, up to 16  | 
  | alphanumerical characters, e.g., "camera web  | 
  | port".  | 
Add (6):  | Add the mapping to the port forwarding table.  | 
Reset (7):  | Resets all values of the input form.  | 
Port Forwarding  | Shows all existing port forwarding rules (port  | 
Table (8):  | mappings).  | 
Delete  | Select a port forwarding mapping by clicking  | 
Selected (9):  | the 'Select' box of the mapping, then click the  | 
  | 'Delete Selected' button to remove the mapping. If  | 
  | there's no existing mapping, this button will be  | 
  | grayed out.  | 
Delete All (10):  | Delete all existing port mappings.  | 
Reset (11):  | Unselect all mappings.  |