1. If you have access to the Tools menu, click the 'Letter Templates' button
2. This screen is split into two halves.
The left hand side will display all the folders that exist in the Letter Templates system folder. See Letter Templates - General Information for general information regarding folder names and location.
The right hand side display the individual letters within the selected folder.
To edit an existing letter, select the folder on the left hand side list and then double click the letter file name on the right hand list.