How to get your API Keys
First, you will need to head over to https://dev.twitch.tv, and click on Log In with Twitch. After signing in click on Launch Console. This is where you will register BTTN with Twitch.tv. On this page click on Register Your Application. The name can be anything but I recommend BTTN. The OAuth Redirect URL can also be anything, but I also recommend http://localhost. Finally, for the category, this can also be anything but I recommend Website Integration. After that click on Create. Then you should be greeted with a screen that shows a Client ID. You will need to use that in the application as well as a Client Secret, which can be generated by clicking the New Secret button. Right this down so you have it when BTTN asks for it.
Adding Keys to BTTN
After retrieving your API Keys from the Twitch Dev website, you can input them into BTTN. Run BTTN in setup mode and select Add API Keys, then enter Y for Add Twitch.TV API keys. It will ask you for both of your keys and save them in the config file specified.