it can feel a little complicated at first. What you're seeing under MC's Playing Now is both a Zone list, and under Playing from xxx Library, MC's library manager. These two areas are merged under this single Playing Now tree. Zones are the first items - Libraries are beneath the collapsible Playing from xxx Library, with the heading indicating which library is in use.
MC and SB both maintain libraries (databases that catalog tracks and their metadata). Typically, when using MC, you're using the main/primary library, and you're directing MC to control playback of the tracks it manages. And when you use your SB via the various SBS user interfaces (web, direct control, etc.), you're directing the SBS software to send tracks to the SB hardware. In both cases, the tracks are directly available to the managing software (MC and SBS).
But with MC and Whitebear, MC is used either to initiate playback of tracks that MC manages, or tracks that SB manages. So how you use it depends on where your tracks, MC, SBS and Whitebear reside, and what features you require.
With DLNA, simply stated, a Contoller (eg. MC here) requests playback operations from a DNLA server (eg. Whitebear), and the server sends tracks to a renderer (eg. an SB).
With MC and Whitebear, there are a couple of ways to accomplish this, and again, how you do it depends on the location of SBS, MC and Whitebear.
When you use Whitebear, Whitebear presents the SBS library to MC, which MC can then import and use playback commands like any other library. This MC library is separate and distinct from the SBS library, and is essentially read-only to MC. And you must switch MC libraries to use it (this means new views, all local playback stops, etc.). For me, this mode isn't useful, as I routinely playback directly on my MC system, and stream to remote SBs in other rooms of the house (wife loves this).
Alternatively if the MC and SBS tracks are one and the same, you can have MC stream directly to an SB. The downside is that cover art is not presented to an SB Touch - you'll see only basic metadata.
Attached is a screenshot showing SB's as zones. In the screenshot, you'll notice that:
a) I'm using MC's Main library (this is the only library I use).
b) To send tracks to an SB, use the Send To command, navigating your way through the tree (there are shorter ways, which I can describe later).
Here, the tracks are located on the MC system. In this configuration, MC streams tracks to the chosen SB. Whitebear in essence negotiates the conversation, and then steps out of the way.
You'll also notice there is another library, that presented by Whitebear (mine is called Le Musica, which is the SBS library as named via SBS). This would be useful if you were not interested in using MC to manage SBS track tags, nor use MC for direct playback. When you use this mode, MC initiates the playback commands, but them Whitebear directs SBS to playback *its* tracks. No streaming. To use this mechanism, you have to load this library (MC will first have to import/build this library). The tracks are located where ever the SBS software resides.
Let's start here, and see what you need next...