To verify plug and play...plug in the USB camera and use the lsusb command before playing
pi@raspberrypi:~/Documents/raspberrypi $ lsusb
Bus 001 Device 011: ID 0ac8:3420 Z-Star Microelectronics Corp. Venus USB2.0 Camera
Bus 001 Device 005: ID 0079:0006 DragonRise Inc. PC TWIN SHOCK Gamepad
Bus 001 Device 007: ID 05ac:921c Apple, Inc. A1082 [Cinema HD Display 23"]
Bus 001 Device 009: ID 05ac:0304 Apple, Inc. Mighty Mouse [Mitsumi, M1152]
Bus 001 Device 008: ID 05ac:0220 Apple, Inc. Aluminum Keyboard (ANSI)
Bus 001 Device 006: ID 05ac:1006 Apple, Inc. Hub in Aluminum Keyboard
Bus 001 Device 004: ID 05ac:911c Apple, Inc. Hub in A1082 [Cinema HD Display 23"]
Bus 001 Device 003: ID 0424:ec00 Standard Microsystems Corp. SMSC9512/9514 Fast Ethernet Adapter
Bus 001 Device 002: ID 0424:9514 Standard Microsystems Corp. SMC9514 Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Start with the Using a standard USB webcam post
pi@raspberrypi:~ $ sudo motion
[0:motion] [NTC] [ALL] conf_load: Processing thread 0 - config file /etc/motion/motion.conf
[0:motion] [NTC] [ALL] motion_startup: Motion 4.0 Started
[0:motion] [NTC] [ALL] motion_startup: Logging to file (/var/log/motion/motion.log)
Then open your browser to localhost:8081