Insert your Windows 7 DVD into dvd rom and boot your computer from DVD Rom.
Now load the setup files.
Select your language to install, time & currency format, keyboard or input method and then click Next.
Click Install now.
Check I accept the license terms and then click Next.
Click Custom (advanced) or Click Upgrade if you already have a previous Windows version
Select the drive where you want to install Windows 7 and click Next.
Installing Windows 7 will start.
Copying Windows files
Expanding Windows files
Installing features.
Installing updates
After that it will automatically restart after 15 seconds or click restart now and continue the setup
After restarting, it will continue the setup. This step will take the most time than the previous steps.
Your computer will restart again...