How do I install Itunes to my iphone?

Hello Pajaha,

Welcome to Apple Support Communities. 

Here’s how to download and install iTunes for Windows: Download and use iTunes for Windows - Apple Support Please note that install iTunes on your computer will not install iTunes to your iPhone.

Let us know if you have further questions.

Take care.

Just to clarify a point made by green500; the reason that iTunes will not be installed on your iPhone is because you do not need iTunes on the phone.

To play songs (music) on your phone, use the built-in Music app.