There are several methods to install Windows 7. You can go for for a clean install, or install an upgrade. If you are a total newbie, I would suggest to go for professional help. On the other hand, if you have previous experience in working with or playing with software, I can offer you a step by step guide for the same.Live....and Let Live!
Installing windows is an sensitive issues. Any wrong doing between the development process can leads to loss of data and defect on your laptop or pc. So, I would suggest to follow the stardard link to install windows 7 on your pc.
Please follow the instructions as described by microsoft for installing windows 7. Link: http://windows.microsoft.com/en-us/windows/installing-reinstalling-windows#1TC=windows-7