Go to Advanced Setup from the main menu and choose Letter Master.

From the Custom Letter Templates screen click on the  button.

Now in the box next to the Letter Name type in the desired name for the letter. In the box next to Group Code fill in the correct code from the code sheet. (Group Code should be always in caps).

Compose the letter using tags wherever appropriate. Tags can be inserted using the Tag drop-down.

Once done, click on Save.