Looking for basic tutorial on wireless transmission

I have a movement sensor device that currently sends analog data (pressure) which I am recording and thresholding to check for movement.
Now I want to turn this device into a wireless one and be able to receive data from it through a PC serial port. I am very new to this whole wireless technology. Could you please show me where to start and point me in the right direction?

It would be nice to run the wireless device on batteries but it's not required. Power is readily available wherever the sensor will be placed. There will obviously be power available on the PC side too.