Yoma, Chapter 4, Mishnah 1. The Mishnah describes the procedure of the lots: how it was determined which of the two goats would be brought as a chatas and which would be sent to Azazel.
"Taraf bakalpi v'he'elah shnei goralos":
The Kohen Gadol would shake the box and mix up the lots inside it, so that he would not know where the lot bearing the Name of Hashem was lying. He would take hold of the lots both at once, so that he would not grope about and sense with his hand which lot was which, and in this way he raised up both lots together:
"Echad kasuv alav laShem" - this is the lot for the goat brought as a chatas to Hashem.
"V'echad kasuv alav laAzazel" - this is the lot for the goat that is sent away and pushed off the cliff.
Those standing at the side of the Kohen Gadol:
"HaSegan mimino" - the Segan stood at the right of the Kohen Gadol.
"V'rosh beis av mismolo" - the head of the family group stood at his left.
The announcement to raise the hand:
"Im shel Shem alah biymino" - if the lot bearing the Name of Hashem came up in his right hand, the Segan, who stood at his right, would say to him: "Ishi kohen gadol, hagbeiha yeminecha" - my master the Kohen Gadol, raise your right hand.
"Im shel Shem alah bismolo" - if it came up in his left hand, the head of the family group, who stood at his left, would say to him: "Ishi kohen gadol, hagbeiha smolecha" - raise your left hand.
"Nasan osan al shnei has'irim":
The Kohen Gadol placed the lots, each one upon its own goat, "v'omer: laHashem chatas". Rabbi Shimon says that he did not need to mention the word "chatas", but rather said "laHashem" alone.
"Hen onin acharav":
When he said "laHashem", the Kohen Gadol would pronounce the explicit Name of Hashem, which we do not pronounce, and the people would answer after him: "Baruch shem kevod malchuso l'olam va'ed", as is customary to answer upon hearing the Name of Hashem.
In summary: In this Mishnah we learned the procedure of the lots: shaking the box and drawing up both lots at once so that the Kohen Gadol would not distinguish between them; one lot reading "laShem" and the other "laAzazel"; the positions of the Segan at his right and the head of the family group at his left, each of them announcing that he raise the hand in which the lot "laShem" came up; placing the lots upon the two goats and saying "laHashem chatas" - and according to Rabbi Shimon, "laHashem" alone; and the people answering "Baruch shem kevod malchuso l'olam va'ed" upon hearing the explicit Name of Hashem.