That's a good effort for a first draft.
There does appear to be a certain amount of overlap with the Wiki, so maybe you could be clearer in the introduction about what this guide provides that the Wiki doesn't, and vice versa. Who is it meant to be used by? When would you use this and not the wiki, or help pages? Could elements be added to the wiki when complete?
One thing that might be useful would be to describe in more detail the concept of the Inbox, and how it is used. I took a little while to get my head around this as it wasn't a feature I had come across before, and the information on the wiki is quite brief. However now I 'get it' I think it's one of the most useful features of MusicBee.
I would like to see an explanation of what happens when you scan for music files, and when you import music from itunes libraries. The following lines in your document are really important to help understand the 'concept' of how MusicBee manages music, and could be at the start of the import section:
"By default, MusicBee will not move any files scanned, only link to their current location. All files that MusicBee finds will be added directly to your Library"
Coupled with this, it is important for a new user to understand the difference between the MusicBee library/database compared with what they might consider as their library (i.e. the directory location on their hard drive or NAS where their physical files reside. This is a key concept as the terms are commonly used in the forums and wiki.