Git Tower将现有文件添加为分支

I'm working on a WordPress plugin that I started developing before I started using Git. At one point, I created a copy of the plugin in a different folder to experiment with an alternate way of writing one part of the plugin. I recently purchased Tower and started using Git to track changes for my plugins. I've created a local repo using the first version of this plugin. However, I'd like to add in that second version I created earlier as a branch of the main plugin.I'm working on a WordPress plugin that I starte