The full Windows 10 has not yet been released; only the Technical Preview is available.
According to this
list, the Lumia 532 is qualified for the Technical Preview of Windows 10.
You may want to read a few articles first before going further. Start with:
Should you install Windows 10 in your phone.
If you decide to install the Technical Preview, this
article should cover your needs.
If you later on decide that the Technical preview is not for you, then this
article shows you how to roll back to Windows Phone 8.1.
P.S.
A bit of research helps.