Installing VirtualBox is just like installing any other application on your Windows OS, so you shouldn’t have any problem with the installation.
To start the installation, double-click on the installer file you’ve downloaded in the previous step:
In the Welcome cindow, click Next:
Select the installation folder and click Next:
Select the way you want features to be installed and then click Next:
Click Yes to install Oracle VirtualBox interfaces:
After a minute or two the installation process should finish.