Q: iTunes osx is taking over my screen.  How to minimize?

Sounds like you accidentally entered Full Screen Mode.

Move the pointer all the way yo the top edge of the screen. When the iTunes menu bar appears, click on the green dot.

Did you try to press esc? Or, View > Exit Full Screen?

If iTunes is running full screen, move your mouse to the top of the screen and the iTunes menu will drop down.

Click the green button on the left under the iTunes menu.

If it's something else, post back.