File templates are files, with default pattern content, used to “pre-fill” newly created documents.
Selection of the file template is done based on extension of new document and name of template: editor searches for file with same extension and name “default” in directory of file templates. To find directory where file templates are located select File→New→Manage File Templates (usually <user-directory>\templates).
You can have different templates for same extension, you can use built-in variables inside for filling default values, you can skip using of the file template by keeping Ctrl pressed when creating new file.
If you want to change default templates directory, you can do this by direct modification of xml setting file.