After your Document Templates are set up, you can access them a couple of ways.
First, you can go to the Documents tab on a specific lead.
From there, you will see the appropriate Document Templates listed depending on the rules you have setup for a given Lead Status.
Then you may click any of the linked Documents to download to your computer.
Open up the document and print it out as necessary.
Second, you may generate documents from the task screen to send or print a document.
For example, if you have a task to "Mail a Rejection letter", you may click the Rejection document template and download the document to print, directly from the task screen.