In other words, to send information across XBees, are serial commands from the computer all that's needed?
What arrives on the XBee's RX pin gets sent over the air. What is received over the air is send to the XBee's TX pin.
The XBee Explorer board connects the serial port TX and RX pins to the XBee TX and RX pins.
So, send serial data from the computer to the XBee explorer board, and the XBee will broadcast it. Whatever it receives over the air, will be sent back to the serial port.
The difficult part in this is configuring the XBees to talk to each other. That's relatively easy using the Series 1 models. It's not so easy using Series 2 models, since the Series 2 models are not designed for point-to-point use.
I could help you with the Series 1 models, but that won't do you any good, since that's not what you have.