Re: Accessing desktop files : have exported some photo images to desktop and want to access them from my iPad
Here's one way:
On the MAC desktop:
Control-click a photo you want to send to your iPad, choose Share from the small menu that opens.

Next: from the Share menu:
You could simply choose to email it to yourself, and open the email on the iPad
or
if you use AirDrop:
you can choose AirDrop and select your iPad that you want to send the photo to.
Using AirDrop: Files sent to your iPad are located in the app that opens automatically when the file is received.
More info: if needed: Use AirDrop on your Mac to send files to devices near you - Apple Support