How do I bootcamp Windows 10 on Macbook Pro? I have a Windows 7 Professional key and the upgrade is supposed to be free, but I have no idea how to go about this. Can anyone please help?

Install W7, reserve your copy of W10 and then do an in place upgrade.

Please see https://www.apple.com/support/bootcamp/ and Use Windows 10 on your Mac with Boot Camp - Apple Support.

Please ensure your Mac is one of the following.

Mac computers that support Windows 10

The following Mac models support 64-bit versions of Windows 10 when installed using Boot Camp. Use About This Mac to see which Mac you have, then check this list to see if it supports Windows 10.

• MacBook Pro (Retina, 15-inch, Mid 2015)
• MacBook Pro (Retina, 13-inch, Early 2015)
• MacBook Pro (Retina, 15-inch, Mid 2014)
• MacBook Pro (Retina, 13-inch, Mid 2014)
• MacBook Pro (Retina, 15-inch, Late 2013)
• MacBook Pro (Retina, 13-inch, Late 2013)
• MacBook Pro (Retina, 15-inch, Early 2013)
• MacBook Pro (Retina, 13-inch, Early 2013)
• MacBook Pro (Retina, 13-inch, Late 2012)
• MacBook Pro (Retina, Mid 2012)
• MacBook Pro (13-inch, Mid 2012)
• MacBook Pro (15-inch, Mid 2012)
• MacBook Air (13-inch, Early 2015)
• MacBook Air (11-inch, Early 2015)
• MacBook Air (13-inch, Early 2014)
• MacBook Air (11-inch, Early 2014)
• MacBook Air (13-inch, Mid 2013)
• MacBook Air (11-inch, Mid 2013)
• MacBook Air (13-inch, Mid 2012)
• MacBook Air (11-inch, Mid 2012)
• MacBook (Retina, 12-inch, Early 2015)
• iMac (Retina 5k, 27-inch, Mid 2015)
• iMac (Retina 5K, 27-inch, Late 2014)
• iMac (21.5-inch, Mid 2014)
• iMac (27-inch, Late 2013)
• iMac (21.5-inch, Late 2013)
• iMac (27-inch, Late 2012)
• iMac (21.5-inch, Late 2012)
• Mac mini (Late 2014)
• Mac mini Server (Late 2012)
• Mac mini (Late 2012)
• Mac Pro (Late 2013)

Has anyone used it on MacBook non-Retina mid, 2012?