Use Boot Camp Assistant in the Utilities folder to create a Windows partition on the hard drive. You will need a Windows 7 retail installer DVD. You will need any USB drive or flash drive that is partitioned using MBR and formatted MS-DOS (FAT32) in order to download the required Windows drivers.
You don't need an OS X installer disc, however, you can purchase Snow Leopard at any Apple retailer for $29.00. You can order replacement discs for the computer at:
Apple Store Customer Service at 1-800-676-2775 or visit online Help for more information.
To contact product and tech support visit online support site.
Go BUY Windows 7 System Builder from a retail store. Amazon, Newegg etc
You are using illegal copy download off torrent.
Schools and others offer students a very cheap download of Windows 7 Pro too.
You won't get help here but you do need to read the manual guide and there are FAQs and help articles Apple prvides
Open Boot Camp Assistant and click on the large button to print the documentation. Read carefully and then proceed following the directions in the documentation.
You will not be able to install Windows using whatever you have from your friend. You need a retail DVD.
You will also need a USB drive you can completely erase. A 2 GB flash drive will work well.