That's pretty broad.
For starters (just to make sure they aren't DOA, try connecting the console cable on each to whatever you intend to use as a serial port (The console port is a SERIAL 9600 baud connection by default, do NOT connect it to your Ethernet port on your computer. Depending on the computer, you may even have to acquire a serial port of some kind (i.e. USB-to-serial).
Once that is connected, power on the cisco device that you have connected with your terminal emulator running (i.e. Putty ?), and you SHOULD get a series of startup messages, indicating ports installed, memory, software version, etc. Take note of these - you may need these later !
Finally, type "enable" when you finally get to the router> prompt. If you can't (it asks for a password that you don't know), you're in for password recovery - which is a whole different topic.
Note that this doesn't "check out" the entire functionality of the device, just checks that the power supply and initial access is OK. This will also let you experience the serial connection on your computer, which isn't covered in any Cisco instrucctional materials.
