Carambola comes with enabled DHCP client and AVAHI services. It means when you connect Carambola to your local DHCP enabled network you can access it by typing http://carambola.local on your browser. You can read here for more details.
Carambola development board is equipped with FTDI USB to Serial converter. After you connect it to your computer it should detect and install drivers for it. New virtual serial port should appear. It responds at 115200 8N1 baud rate.
For a beginning you can mess around with settings using preloaded LuCi web interface.