Hey Paul,
From everyone's response this seems like a real simple process but i seem to be having so much trouble with it. whenever i try to run the 'fastboot-windows oem unlock' in the command prompt i get 'INFO [ERR] Command error !!! OKAY' i attached a screenshot of my desktop with each of the folders open, please help me out it'll be greatly appreciated!
EDIT: I just read one of the comments below where he dragged the AdnWinUsbApi.dll file and it worked for him. when i did that and tried running the oem unlock command i got 'FAILED <status read failed <Too many links>>'
HTC Desire Z
Android 2.3.3
HTC Sense 2.1