So firstly make sure you have the following:
- 8GB USB Flash drive
- Windows 7 disc or iso image
Once you have these then you need to go to spotlight and type bootcamp and select the assistant.
Press continue on the first screen and then select the top two options, the first option will setup your flash drive to have the windows 7 iso image on the flash drive. The second option downloads all the necessary drivers for your mac to operate correctly under the windows operating system. We dont need the drivers until you have installed windows but best to get them ready as its a big download.
The next screen will require you to locate your windows 7 iso and then the destination drive(which is your flash drive). The flash drive will be formatted so make sure your drive doesnt have anything important on it as its going to get wiped.
Then the next screen will ask you to download the windows drivers, select the bottom option to save it on disk and then put this in a folder on your mac for now as we will need it later.
Once you have done that you need to setup the partition on the hard drive of the mac, adjust the selector, you will need at least 30gb, my recommendation is around 50gb.
Once this is done, restart the mac with the usb drive inserted, it will go through the normal windows installation, you will be presented with selecting a partition to install to, select the partition labelled bootcamp. You will then need to click format so that Windows can format it with the needed file system.
Then go through the whole of the windows installation, once this has completed when you boot into windows for the first time then the resolution and stuff will be all messed up, you need the mac drivers so you will need to remove your flash drive and restart the computer. If you hold down ALT on startup you can see the disks to book from, make you selected mac this time and then when you back in Mac OS you need to locate the folder where you downloaded the drivers and copy this to your usb flash drive, after that then restart your mac and hold the alt key and selected Windows.
When you back in Windows, locate your flash drive and run the setup.exe file from the drivers folder, this will install all the drivers, you may need a restart but after that then you are good to go, so whenever you want to go into windows, just hold ALT and then select the drive.