Pro Audio
Design and Skin Customization
You're going to need to edit your skin templates. Checkout these docs. - https://www.jamroom.net/the-jamroom-network/documentation/jamroom-admin-handbook/3183/using-the-template-editor
The index.tpl and its included templates control the homepage whereas the profile_footer.tpl template is where you'll likely want to put the Google Ad script.
Hope that helps