If you want to change the logo to your own, this is where to do it. The logo by default is PlayoutONE LiveStreams, and this appears on emails sent out.
Simply click 'Choose Logo' and you will get a file chooser window where you can locate the file you want and click 'Open'. This will then change the logo you see in the Logo section.
To reset the logo back to the default click 'Reset Logo'.
The Width is just so you can adjust the logo width on the email. You may or may not need this.