Hebrews 5  begins with a definition of what a "high priest" is:

He is a man "taken from among men" 
He represents all men "in things pertaining to God"
He offers gifts and sacrifices to God  "for sins"
He is to "deal gently with the ignorant and misguided"
He is not without sin himself, so he offers sacrifices for his own sins along with others.
He is called, anointed, and appointed  to this position by God... he does not elect himself to it.

Beginning with verse 5, the writer describes Jesus, the great high priest:

He is the Begotten Son..
He did not elect Himself, but was appointed by the Father "Thou art a priest forever according to the order of Melchizedek".   
He "offered up both prayers and supplications" to the Father.
He was heard "because of His piety".
He learned obedience from His suffering.
".. and having been made perfect, He became to all those who obey Him the source of eternal salvation." 

Jesus became a man so that He could represent all men "in the things pertaining to God".  He offered the only acceptable gift, the sacrifice of His own body, for all sin.   He deals with us gently, for we are all ignorant and misguided.  Unlike the high priests from Aaron's line, Jesus was without sin, so He did not offer sacrifices for Himself, but for us.  He is God's anointed One,  glorified by the Father, as He perfectly fulfills the role of High Priest forever. 

In verses 11-14 the writer explains that those dull of hearing, immature believers, cannot grasp all that he wants them to understand. We need to know the "elementary principles of the oracles of God", the milk, before we can move on to the "meat", the "word of righteousness".  We need to gain maturity.. we need to "practice" what we have learned... to have our "senses trained to discern good and evil." 

Father in heaven, we glorify You, our loving God, who has given us such a Great High Priest, Jesus, the only begotten Son of God.  He is our Perfect representative, and sits at Your right hand.  He offers intercession for us, for we are often still ignorant and misguided and sadly immature.  Father, lead us to completeness, to purity and righteousness in Christ our Lord.  Forgive us our sins and help us as we forgive others who have sinned against us.  Lead us away from temptation and into Your perfect ways. We desire to worship and obey.  Fill us with Your own Spirit that we might walk with You in peace..  We ask this in the Name of our Lord Jesus Christ, amen.