Display second menu only on some page

I am new to WordPress and I have been trying for days now without success. I have two Menus on my website. How do I set my second menu from not showing up on all the pages? I just cant figure this out. I have watched many tutorials and read beginners manuals but they only talk about building menus. I just cant seem to figure this out.

1) How do I display a menu on certain pages only?

2) how do I control what menu Items are displayed on a specific page?