Hi Asim,

If you want to have two operating systems installed in your machine at the same time, you can follow the steps mentioned below to do so.

Step 1. You can download Ubuntu in the form of an .iso file, which is an image file of a CD--in this case a bootable one. Double-click the file, and a program will likely come up and walk you through the process of burning the disc.

Step 2. If no such program pops up, download and install the Active@ ISO Burner, then try again.

Step 3. Now you have 2 options for using Linux on your PC.
Option 1: Installing witihin Windows

• Install Ubuntu Within Windows
• You can actually install Ubuntu as a Windows program, although you can't launch it as one.
• Insert the CD or flash drive. If nothing starts up automatically, open the drive in Windows Explorer and runwubi.exe. Select the option Install inside Windows, and follow the prompts.
• When you reboot after the install, your PC will boot Linux and start setting it up. This can take a long time--especially if you're using a CD. Be patient.
• The next time you boot, and with every boot afterwards, you'll get to pick between Windows and Ubuntu. And you can uninstall Ubuntu like any other Windows program.

Option 2. Install Ubuntu in a Virtual Machine

• You can run both OSes simultaneously by installing Ubuntu inside a virtual machine (VM). In a VM, software imitates hardware so that you effectively run one computer inside another.
• I can recommend two free VM programs: VMware Player and Oracle VM VirtualBox.
• Ubuntu installs just fine in either of them. 
• VirtualBox is more powerful, but I find VMware Player easier for the virtual machine novice.
• By the way, you don't actually need to burn a CD or prepare a flash drive to install Ubuntu inside a virtual machine. Both VMware Player and Oracle VM VirtualBox can install directly from the .iso file.

I hope this helps in installing Linux successfully in your Windows machine.

Regards,
Lokesh