https://api.twitch.tv/kraken/users/USER/follows/channels/CHANNEL_TO_FOLLOW
In this link, the user is USER, and the channel is CHANNEL_TO_FOLLOW. As far as gathering the username and channel name goes, that’s up to the web developer. Since this requires the application to be authenticated with the user_follows_edit scope, I would suggest making a call to to the api root with the token to get the username (Documentation).