How to connect to iTunes Store?

Tap iTunes Store app on the Home screen.

If you don't see it, use App Library to search iTunes Store app, see this Apple article:

Organize the Home Screen and App Library on your iPhone

Organize the Home Screen and App Library on your iPhone - Apple Support           

If you have find the app, tap & hold on the app, then drag to the Home screen & drop it.

See the Apple Support article(s) below. 

App Store, iTunes Store, or other Apple services - If you can't connect   *