I have got the BB Black for a while but never got time to get started. It is different from Raspberry Pi in some sense.
The thing which I liked is that it can boot from an onboard emmc memory chip. This means you do not need to install OS on
fragile SD cards.
It comes with the installed OS when purchased. So, just plugging it via the USB cable supplied with it will start the boot process.
The default username and password is the following
After the power on BB Black will appear as a new drive on PC.
In Chrome or Mozzila enter the IP 192.168.7.2 to get access to the board.
One can get access to the command prompt of the board the via serial or ssh protocols
the baud rate of 115200 and with /dev/tty**** (your_device).