On the 16th day of Nisan, the barley to be used in the Omer offering was harvested in a grand public event. Residents of the villages surrounding Jerusalem would all come out to take part in the joyous occasion.
After completing the harvest, the kohanim, (priests), would bring baskets filled with barley to the eastern side iof the inner Temple courtyard. There, the newly ripened grain was beaten, roasted, and sifted in thirteen sieves. A handful of the flour was burned on the altar, and the rest was eaten by the kohanim.
Torah states that the first grain offering must consist of fresh barley kernels roasted in a perforated pan, and then ground into a coarse meal. "You must place olive oil and frankincense on it... " (Leviticus 2:15)
Next, the kohen must "wave the Omer before G-d." (Leviticus 23:11) This was done in front of the northeast corner of the altar, the kohen facing westward.
The final step of the Omer offering involved the kohen scooping out a handful of flour from the meal mixture and placing in on the fire atop the altar. This was followed by the bringing of a single male sheep as a burnt offering. From this point on, grain from the new harvest could be eaten.
After waving the Omer at the northeast corner of the altar, the kohen presented the first grain offering before the southwest corner of the altar. This was standard procedure for nearly all meal-offerings.
Following the conclusion of the Omer offering in the courtyard of the Holy Temple, pilgrims leaving the Temple would find the marketplaces of Jerusalem already overflowing with grain products from the new harvest.