It is quite easy to add a new project template. It's probably easiest to copy an existing one and edit it rather than starting from scratch.
Each project folder needs three things inside it;
When the files are copied from the Files subfolder, any instance of the string $PROJECT_NAME$ is replaced with the project name. For this reason, you must have a file called $PROJECT_NAME$.lnp in your template folder! It's not just the filenames that are adjusted - it's also the content of the files themselves.
The .lnp file is simple XML document that can be edited in any text editor.