The passage from Hebrews 9 describes it this way:
1 Now the first covenant had regulations for worship and also an earthly sanctuary. 2 A tabernacle was set up. In its first room were the lampstand, the table and the consecrated bread; this was called the Holy Place. 3 Behind the second curtain was a room called the Most Holy Place, 4 which had the golden altar of incense and the gold-covered ark of the covenant. This ark contained the gold jar of manna, Aaron’s staff that had budded, and the stone tablets of the covenant. 5 Above the ark were the cherubim of the Glory, overshadowing the atonement cover.[a] But we cannot discuss these things in detail now. (Hebrews 9:1-5)It can help to see a plan as well:
Eventually the tabernacle was replaced by a Temple in Jerusalem - built by king Solomon. This was destroyed when Jerusalem was captured by the Babylonians. The second temple was finished around the time of Jesus and looked something like this (it was destroyed in A.D. 70):
So what was the value of this ministry? The writer to the Hebrews is clear that it was not really satisfactory - that it couldn't really 'clear the conscience' - it couldn't really provide forgiveness of sins:
6 When everything had been arranged like this, the priests entered regularly into the outer room to carry on their ministry. 7 But only the high priest entered the inner room, and that only once a year, and never without blood, which he offered for himself and for the sins the people had committed in ignorance. 8 The Holy Spirit was showing by this that the way into the Most Holy Place had not yet been disclosed as long as the first tabernacle was still standing. 9 This is an illustration for the present time, indicating that the gifts and sacrifices being offered were not able to clear the conscience of the worshiper. 10 They are only a matter of food and drink and various ceremonial washings—external regulations applying until the time of the new order. (Hebrews 9:6-10)
The great news is that Jesus has a better priesthood - because he is sinless and because he offers himself as the perfect sacrifice for our sins. His sacrifice is made once and for all time on the cross of calvary, but it is also said to be made in the true, heavenly sanctuary.
24 For Christ did not enter a man-made sanctuary that was only a copy of the true one; he entered heaven itself, now to appear for us in God’s presence. 25 Nor did he enter heaven to offer himself again and again, the way the high priest enters the Most Holy Place every year with blood that is not his own. 26 Then Christ would have had to suffer many times since the creation of the world. But now he has appeared once for all at the end of the ages to do away with sin by the sacrifice of himself. 27 Just as man is destined to die once, and after that to face judgment, 28 so Christ was sacrificed once to take away the sins of many people; and he will appear a second time, not to bear sin, but to bring salvation to those who are waiting for him. (Hebrews 9:24-27)In chapter 10, the writer of Hebrews urges us not to waste the privileged access we now have to the Father through Jesus:
19 Therefore, brothers, since we have confidence to enter the Most Holy Place by the blood of Jesus, 20 by a new and living way opened for us through the curtain, that is, his body, 21 and since we have a great priest over the house of God, 22 let us draw near to God with a sincere heart in full assurance of faith, having our hearts sprinkled to cleanse us from a guilty conscience and having our bodies washed with pure water. 23 Let us hold unswervingly to the hope we profess, for he who promised is faithful. 24 And let us consider how we may spur one another on toward love and good deeds. 25 Let us not give up meeting together, as some are in the habit of doing, but let us encourage one another—and all the more as you see the Day approaching. (Hebrews 10:19-25)
What a great privilege to 'boldly approach' the God of the Universe knowing that we are forgiven through the blood of Christ and that he longs to hear our requests!