Read carefully Hebrews 2:17 – 2:18
17 Wherefore in all things it behoved him to be made like unto [his] brethren, that he might be a merciful and faithful high priest in things [pertaining] to God, to make reconciliation for the sins of the people.
18 For in that he himself hath suffered being tempted, he is able to succour them that are tempted..

You would see a parrallel to John 17:19: And for their sakes I sanctify Myself, that they also may be sanctified by the truth.

As we all know the name,ADAM means the father of the human race. life can only be passed on by birth. so when Adam sinned, he introduced a disease called sin into the lifestream of humanity. Mans nature became corrupted and this was the only characteristics Adam could pass on to his children. that is why we are all in a sinful state because we all inherited the fallen life of adam. even so, in the same manner of speaking, Jesus Christ, as the last Adam,the Father of the new human race, must possess in Himself certain characteristics to pass on to His children. that was why it was necessary for Jesus to become a man(like unto his brethen) in the fullest sense;so in this position,He felt the power of our temptation,He conquered it and He suffered and was SANCTIFIED or perfected in that life of victory which He seeks to possess for our sake( read Heb. 5:8-9) as a result, He was qualified to help me. He could not have been able to help those in that position where the first Adam put us, if He had not pass through it Himself. Jesus was not the author of eternal salvation until He had suffered, and was perfected in that life, before He could pass it on to us through NEW BIRTH

Hebrews 5:8 – 5:9
8 Though he were a Son, yet learned he obedience by the things which he suffered;
9 And being made perfect, he became the author of eternal salvation unto all them that obey him;