So what have you done so far? Did you go to the Brother website and get Windows 7 or Vista drivers.... and for whichever version of Win7 you are running... 32 bit or 64 bit? Did you then install the software... BEFORE connecting the printer to the PC? If you connected before you installed, now you need to undo what you have done the wrong way round. Disconnect the printer, uninstall the software and reboot the PC. (http://www.coribright.com/windows/Article_One.htm). Do NOT omit Step 4.
Once the PC has restarted, install the software and do NOT connect the printer until the software tells you to do so.