how to install itunes on my ipad

You cannot install iTunes on an iPad.

iTunes as a service was re-branded some time ago as Apple Music. At the same time, the related Apps on Mac, iPad and iPhone devices were similarly renamed.

iTunes as an App remained with Mac until its functionality was subsumed into Finder and the new Music App - at which time references to iTunes disappeared.

Information about macOS Finder - and its use with iPad - can be found here:

Use the Finder to sync your iPhone, iPad, or iPod touch with your Mac - Apple Support

Locate and view your iPhone or iPad on your computer - Apple Support

If your device doesn’t appear in the sidebar when connected to Mac - Apple Support

Why do you think you need iTunes on your iPad?

iTunes is a Mac or Windows app, it does not run on iPads.

What are you trying to accomplish exactly?