updating ipad

Ok that's fine.

You have an iPad Air 1st gen which can be updated to iOS 12

So what happens when you try and open iTunes on your computer?

What happens when you plug the iPad into the computer?

See if any of these support documents will help you -

Download and use iTunes for Windows – Apple Support

Update your iPhone, iPad or iPod touch – Apple Support

Try this support link, which I did post above - Update your iPhone, iPad or iPod touch – Apple Support

You are being very vague so it's hard to help, so if you can provide more info that would be helpful

Which iPad do you have? Which iOS is it running?

If you go

Settings - General - about -

The if you can provide

Software version -

Model number -

Thanks