Consequently, Jesus is able for all time to save those who approach God through him, since he always lives to make intercession for them.
For it was fitting that we should have such a high priest, holy, blameless, undefiled, separated from sinners, and exalted above the heavens. Unlike the other high priests, he has no need to offer sacrifices day after day, first for his own sins, and then for those of the people; this he did once for all when he offered himself.
(Church in Wales Lectionary, New Revised Standard Version)
Have you ever thought about why Christians often say "through Jesus Christ, our Lord," at the end of prayers? Well these words from the Letter to the Hebrews, explains why. The writer says that up till then the High Priest has offered animal sacrifices to God for their own sin and for the sins of the people. To us this seems cruel and strange, but perhaps God required this because the constant killing and cost, would remind the Jews constantly of their sin.
For Christians Jesus is the High Priest, and the sacrifice of His life is the one and only sacrifice that needed to be made. Because He lived a blameless life, and because he understands our human condition, He can pray for us and intercede for us continually to the Father.
And the "Amen"? Well that's just, "So be it, Lord," or as I like to think, "I'm asking, Lord, but it's up to You!"
Lord Jesus,
we know we sin,
even if all too often
we choose to forget this.
Forgive the times we turn from You;
the times we ignore our wrong-doing;
the times we push our mistakes from our mind;
and help us to be honest with You,
and ask for the Father's forgiveness.
Then give us the courage to leave
the answer to Him.
Amen.
You might like to look up this site for a fairly simple explanation of this passage from Hebrews: