How Can I Control a Windows PC from Apple Remote Desktop Please?

Apple Remote Desktop is intended to be used between Macs. You can not use it to control a PC. You will have to use VNC, Microsoft Remote Desktop, or another product that is cross platform. ARD is not.

You can use ARD to remote control a windows machines, ARD is built on VNC

You'll have to install a VNC server on the windows machine you want to access

You won't be able to use most of the ARD features as they are specific to mac

You'll be be able to see and control the desktop and that's about it

You can also find VNC /Remote Desktop apps in the iOS store that will allow remote desktop connection from iPad /iPhone,

There is a mac version of Microsoft remote desktop in the Mac App Store

There is eeasy Software called Teamviewer this can be used accross multiple platforms also on a mac you can make it run like a windows PC when you first get it

To avoid awkward configuring etc just install a remote access product which will work out of the box: NoMachine for Mac on your Mac, NoMachine for Windows on your Windows. Dead easy

have a look here

http://helpdeskgeek.com/networking/connect-to-windows-pc-apple-remote-desktop/

you might have to add the windows machine manually into ARD

and maybe either change to ports VNC uses to match the ports your using for ARD

Try this one:

https://itunes.apple.com/de/app/microsoft-remote-desktop/id714464092?mt=8

Its relly great and free!

I am not sure if you can control UAC with VNC, thats why I prefer this free app from M$

That MS product is great, but not what the OP requires.
He wants screen sharing/viewing, not Terminal Services client.

The MS product creates a new login session 'behind the current user's desktop) on the PC or locks the screen with a message that it is in use -depending on Windows version.