The sacrificial system of the Old Testament is not a common discussion topic or a matter of popular study in the 21st century church. The Temple where these sacrifices had to be offered was destroyed by Titus of Rome in AD 70 and has never been rebuilt. The practice of offering the blood of lambs, goats, bulls, etc. to cover the sins of the people has not been officially practiced since that time. For Christians this older system was "done away with" when Jesus offered his own life as the final atoning sacrifice for the sins of the world. This final sacrifice -- the offering of the Son of God -- fulfilled the Old Covenant requirement "that without the shedding of blood there is no forgiveness of sins (22)" and was completed "once for all at the end of the age to remove sin by the sacrifice of himself (26)."
This argument is the same one the author of Hebrews is making throughout this letter. The argument is simple: Jesus replaces all of the Old Testament requirements. Remember the context of the letter to the Hebrews is that some Jews who had become Christians were returning to their former ways and life in Judaism. The author of Hebrews is writing to show the folly of this behavior and, perhaps, to convince them to return to the church. The discussion here in chapter 9 and 10 is one of the reasons this letter is usually dated in the late 60's. It seems inconceivable that the author would fail to mention the destruction of the temple in Jerusalem had that destruction already happened in light of his argument that the work done in the Temple was no longer necessary because of the offering of Jesus on the cross. The argument goes: since the destruction of the temple (and the city of Jerusalem) occurred in AD 70 and this event is not mentioned in Hebrews, the letter had to be written before that date.