It's easy to install dual OS, but if you install Windows after Ubuntu, Grub will be affected. Grub is a boot-loader for Linux base systems. You can follow the above steps or you can do just the following:
- Make space for your Windows from Ubuntu. (Use Disk Utility tools from ubuntu)
- Install Windows on freed space.
- After installing, login to windows
To fix this you can install 'EasyBCD' in Windows.
Download it here
Follow these steps to restore GRUB when after installing EasyBCD:
- Launch the program and select ADD NEW ENTRY from the EasyBCD Toolbox
- Select the 'Linux/BSD' from the operating systems column
- Choose GRUB (Legacy) under type and click on the ADD ENTRY icon
- Choose YES to the restart prompt
GRUB will be displayed after the restart and will detect the Ubuntu partition for you to be able to boot into Ubuntu.
logical partitionswhich allows you to have almost any number of partitions.