How do I launch Bonjour?

Unless you’re running a firewall behind a NAT router (which serves no point), Bonjour’s enabled and running by default. It’s used to discover and connect to other devices within your local network configuration (think of that W2P button on a router - it’s Apple’s software equivalent). To view Bonjour discoverable devices through Safari, go to:

Safari > Preferences > Advanced > “Include Bonjour in The Bookmarks Menu.”

I’ve never set up a WD MyBook “NAS”, but here’s an example of how Bonjour works through Safari.

The printer on my local network (S-2) is discoverable:

I’m able to manipulate its settings via my browser:

You have to include it yourself. In Safari go to 'Preferences' > 'Advanced' and select "Include Bonjour" where you wish to - either in Bookmarks or in your Favorites bar.