add a second bookmark toolbar

Firefox doesn't have a built-in feature for this (either a separate second toolbar, or a two-line toolbar). Can you use folders on the bookmarks toolbar to get access to everything you want quick access to?

some of the youtube videos show a totally different cuatomize dialogue box than what i get on my program, why is that?

Those videos may be using a much older version of Firefox.

some of the youtube videos show a totally different cuatomize dialogue box than what i get on my program, why is that?

There have been a lot of changes over the years. The latest major change involved the Extensions button drop-down: you need to pin an extension toolbar button to the bar there first before you can Customize it to a specific location on the bar (and you can no longer move it to the overflow menu). (Manage your extensions using the extensions button in the toolbar)

But I can't remember any Customize dialog that let you add a second bookmarks toolbar, or a second row to the bookmarks toolbar.