where can i find official microsoft presentation of PowerPoint for Windows 8.1?

Your question is not clear, would you mind clarify it?

Are you looking for Microsoft Office PowerPoint installation file?

Or are you looking for some slides explaining Windows 8.1?

Hi Naqash Ahmed,

Are you going to introduce Windows 8.1 ?
I haven`t heared there is any official powerpoint documents for downloading.

If you want some useful information ,here is a link may be useful
What's new in Windows 8.1
https://technet.microsoft.com/en-us/windows/dn140266.aspx

Best regards