How do this? please give me some instructions
As far as I know, Nextcloud, (or ownCloud) is not supported as a server install on Windows. If you are only looking for the clients, they are downloadable at https://nextcloud.com/install/#install-clients
Nextcloud Server is not suitable for Windows anymore. (Owncloud was before).
They had problems with Windows Folders, i tested it was a disaster as soon as someone put a file with an accent é à etc…
You can still download wamp or xampp for installing nextcloud on windows but you will be on your own, like for Mac Os X.
You can use the official VM as a VM in Windows 8. Download it here: https://www.techandme.se/nextcloud-vm/
+1 @enoch85, super simple alternative to a potential nightmare if Windows is your only choice.