A metaphor is a figure of speech, in which phrases or words are added to a object that is not actually literally applicable.
The metaphor in firework by Katy Perry is "Because baby your a firework". Katy perry was trying to say that inside everyone bright, loud, full of life, unique and beautiful.
The metaphor in Waterfalls "Don't go chasing waterfalls" is a way of expressing how people chase intangible dreams and not thinking about the consequences
The metaphor in Titanium "You shoot me down but I won't fall, I am titanium" it means that you are strong nothing you do will hurt me, titanium is the strongest metal
This passage "The teaching of the wise is a fountain of life." The metaphor is "A fountain of life" Which means that the teaching from the wise will help you survive in a world full of sin.
This passage "But now, O Lord, You are our Father, We are the clay, and You our potter; And all of us are the work of Your hand." The metaphor is "We are the clay, and You our potter" Which means that god shapes us into who we are and what we stand for.
This passage "The Lord is my shepherd, I shall not want." The metaphor is "The Lord is my shepherd" Which means that the Lord will lead us in the right direction and help us, if one of us strays onto the wrong path or gets lost he will come find us and help us to follow him again.