Some days ago i used Ubuntu 14.04 LTS for 2 weeks and loves it. On that time i had completely install Ubuntu on my laptop. Now the problem is i also has to developed .Net applications. So i need both Windows and Ubuntu on my laptop.
1 - First I tried to install on Oracle Virtual Box, but found that my laptop doesn't support visualization. So it can't be install via Virtual Box.
2 - Then i tried to install Ubuntu alongside windows but see that there was no option given for such.
3 - Then i free up some space on my hard drive and try again, and see that no un-allocated space was shown during installation Ubuntu.
then i read this article,
when i run Confirm-SecureBootUEFI command on powershell, it says Cmdlet not supported on this platform
Seeing from the screenshots, your hard drive contains no operating system at the moment, which means you have to install both OSes from scratch. You should install Windows first, then Ubuntu, choosing to install it alongside the existing installation of Windows.
You can find information about installing Ubuntu alongside Windows on the WindowsDualBoot help article from the Ubuntu website. You should install Ubuntu after Windows for the reasons mentioned in that article. The line "Cmdlet not supported on this platform" in your post means your laptop does not feature Secure Boot, so there should be no other steps required.
Once both systems are installed, GRUB2 (Ubuntu's default bootloader) will allow you to choose between Windows and Ubuntu at every startup.