"This is the law of the sin offering, chatat: at the place where the elevation offering, olah, is slaughtered shall the sin offering be slaughtered before G-d, it is holy of holies" (Vayikra 6:18).
The kohen gadol performed vidui, confession, three times on Yom Kippur. The first two were done using his own personal bull offering, asking for forgiveness for the sins of his family and for his fellow kohanim. The third vidui, for the sins of the people of Israel, was done with the shair hamistalech, the "scapegoat" that would then be led off to the desert and hurled off a mountain.
"G-d wanted to give merit to the Jewish people; therefore, He increased for them Torah and mitzvoth". A Jewish way of life offers so many opportunities for mitzvoth. We accumulate mitzvoth--and hence, merit--for such things as saying good morning to a passerby, conducting a business transaction honestly, showing up in shul to hear shofar, eating a meal on Shabbat, and many other activities that are both easy and enjoyable.