The easiest way to either mirror or extend your PC's display is by pressing the combination of the Windows logo key + P. To mirror your display, select "Duplicate" – to extend it, select "Extend". This is what it should look like:
If you want a more in-depth explanation on how to mirror or extend your display on Windows, check this out: https://support.microsoft.com/en-au/help/4340331/windows-10-set-up-dual-monitors
After establishing a connection between your Mac and iPad, go into Settings > Adjust Display Settings
After selecting "Adjust Display Settings", you'll see a new menu with all available resolutions and the option "Mirror Display". If Mirror Display is checked, you'll mirror your Mac's display – if it's unchecked, you'll extend your Mac's display.
If you have any trouble throughout the process, please reach out to us at firstname.lastname@example.org – we're always happy to help out!