Free will is perfect in its freeness. Free will's perfectness to choose free will is given by God. God did not give us perfect knowledge. God said don't eat of the tree of good and evil. Perfect free will needs to be given its perfect choice to sin having God made this perfect free will in His image.
You should know about this free will because God has given it to you. So as to take responsibility for yourself to choose God.
You are misunderstanding what perfect will means. Perfect will means it is the same will as God's. The only reason God never makes a mistake with that free will is because He is God. The reason we make mistakes with our free will is because of the fall of Adam and Eve. That is all. You have noone to blame except the first man and first woman, and thus yourself.
I forgive you for jumping at me. Or for thinking I am calvier. If you choose not to accept God's image of you in your free will and think you are an automaton, I will hand such a thing back to God to deal with.
You seem to be asking for a verse. Here it is. Plus read the story in the garden.
Gen 1:26 And God said, Let us make man in our image, after our likeness: and let them have dominion over the fish of the sea, and over the fowl of the air, and over the cattle, and over all the earth, and over every creeping thing that creepeth upon the earth.
Gen 1:27 So God created man in his [own] image, in the image of God created he him; male and female created he them.
