If you wanted to just make a player the shows the team member with the most viewers at the moment, I made something for this a while back. It will need work and probably some updating (update the iframe/player for the latest documentation) for helix (currently using v5) but I think it can get you started: http://twitch.apiexampl.es/teams.php.txt
Also, on wordpress I would use a plugin like “XYZ HTML Snippets” to insert code blocks of php.