For letters to be created within CCD, you will need to setup a word template.
You will find this within Setup> Technical> Applications> Word processing> Configure setup for MS Word.
Once the word configuration window appears, you will need to click the folder icon next to the 'Template file' field. Browse to the template file and select 'Open'
This has now saved you template file location. Every time you generate a letter, it will use this template.