Whenever the High Priest sinned or whenever the people sinned as a group, the sin was confessed and the blood of the animal that was sacrificed was registered on the horns of that particular Altar of Incense. This information can be found in Leviticus 4: 1-13, since the sin of the anointed priest included the whole Congregation in corporate sin.
Part 2 is found in Leviticus 4:13-18 when it was the sin of the Congregation. In both categories there was a record of confessed corporate sin which was registered on the horns of the Altar of Incense in blood.