For Presenter 5 and Web Creator 2, 3, 4 and 5, use the feature Background sound in Project properties. 

Background sounds are not generally recommended. 
They can be perceived as intrusive for the visitor as they cannot be stopped or controlled when viewing the page and can cause conflicts with other applications also using sound. 
Dramatic reduction in return visits  and visits duration can be observed when a website has a background sounds, so it is considered as having a negative impact on a website visibility and promotion. 

If sound is relevant to the subject of your website and you wish to present your visitor with the option of listening to some sound files while browsing your website, it is best to insert a sound player, such as an MP3 player, which will play songs continuously across pages, and will give the visitor an option to change tracks and turn the music on or off. Such players are available on the web from different sources depending on your needs, and can be inserted like any external code or javascript in Web Creator.