Shift click the application to specify the Music library path
By default, under settings the drive that is selected as where to sort from, is the D:\ drive, so you first have to put your new music there, then drag it into musicbee, and it will move and sort these tracks in your library.
What I like to do is to turn on the wavebar on the bottom pannel and set it to 100px
For skin I use Dark Metro Series → Dark Cobalt.