Currently there are 2 options to setup your homepage content.
Open Theme Setting > Homepage and Select homepage gallery. You can also change homepage gallery style there. Next you can insert music to your homepage gallery. Simply upload .mp3 file and click "Insert to post" button.
If you select "static image" as homepage style then you can upload background image in "Static Background Image Settings".
You can also setup homepage content as static page. From your admin sidebar, open Settings > Reading> Front page displays then select "static page".
Note: Theme documentation's located in your downloaded file from Themeforest. Please follow the theme's instructions in /manual/index.html it will help you get through all theme features.