How to install Debian in windows(Oracle VM virtual box)

First to install Debian OS in our virtual box we need
1. Oracle VM Virtual Box
2. Debian OS

1. Oracle VM Virtual Box
      Can be Downloaded here
Select the required platform as shown below

A exe file will be downloaded with name as VirtualBox-Version
Double click the file and follow the instructions(Mostly yes for every option)

2. Debian OS
     Can be downloaded here
Select your processor and download the image file.

Now open the Virtual Box program and click on New tab which is at left top most side.

A small tab will be opened where we have to name the operating system which is Debian in our case,
soon after typing Debian in the name field the 'Type', 'Version'  will be automatically displayed.
Click Next now

Now select the Memory size which is the RAM that should be allocated to this OS while it is active state.
For our system to run well let it be half of our original memory.
If your memory is 8gb select upto 4gb.
Then click next.

Now select the default option that is "Create a virtual hard drive"
and click Create option.
Select the default Hard drive file type that is "VDI".
and click Next option.
Now select the Location and size for your newly created VDI,
by default it is 8gb
click next if 8gb is enough for our new OS and its files,
Or select the size you need for our OS.
My recommendation is to select about 12gb.
Now click Create.  A new subfolder is created in our VM VirtualBox folder.

A new OS will be Displayed with the name Debian in the OS tab which is on our left side.
Click the OS you need that is Debian in this case.

Now we need to Select the Start-up disk, in this case the Virtual Box automatically searches for the Debian image file.
Now click on Start option to start the VM.
If the image file is not listed there we need to navigate to the Debian image file which is downloaded before.