We are commanded to hear the blowing of a horn (shofar) on Rosh ha-Shanah, as it says "It shall be a day of blowing the horn for you".¹ In the Temple the shofar was accompanied by two trumpets, as it says "Blow trumpets and sound the horn before Ha-Shem the King".^2,a If one of the days of Rosh ha-Shanah falls on the sabbath the horn is not blown on that day except in places where there is an ordained rabbinical court.^b It is customary to blow the horn after the reading of the Torah and also after each of the three intermediate benedictions in the shemoneh esreh of the additional service.^c

b) The Booth

We are commanded to live in a booth (sukkah) on Sukkos, as it says "You shall dwell in booths for seven days"³; during that time one must use the booth for regular meals and the like, but he can use his house in an incidental way or if using the booth would cause him excessive discomfort (in particular when it rains).^d The booth must have three walls and must be roofed with plant growths that have been detached from the ground and that are not susceptible to impurity.^e

c) The Palm Branch

We are commanded on Sukkos to hold a palm branch (lulav), a citron(esrog), three or more myrtle twigs and two willow twigs [as it says "And you shall take for yourselves on the first day] the fruit of a beautiful tree, palm branches, a branch of a thick tree and willows of the stream".^4,f They must be held upright and waved at certain times during the reading of hallel (Psalms 113-118, which are recited after the morning shemoneh esreh on new moons, festivals, and Chanukah). It is also customary to carry them around the synagogue once on each of the first six days and seven times on the seventh day, just as they were carried around the altar in the Temple.^g Originally this commandment applied only to the first day of Sukkos, except in the Temple where it applied to all seven days, as it says "And you shall rejoice before Ha-Shem your G-d for seven days"⁴; since the destruction of the Temple it was instituted on all seven days (except the sabbath) everywhere.^h It was also traditional in the Temple to put willow branches against the altar on each of the seven days.ⁱ Sukkos in the Temple was an especially joyful festival, as it says "And you shall rejoice before Ha-Shem your G-d for seven days"⁴; it was celebrated with dancing, singing, and playing on musical instruments.^j

Sources:
1. Num. 29:1	a. 1:1-2
2. Psalms 98:6	b. 2:6,8-9
3. Lev. 23:42	c. 3:10
4. Lev. 23:40	d. 6:2,5,10
	e. 4:2; 5:1
	f. 7:1-3,7
	g. 7:9-10,23; Chanukah 3:6ff.
	h. 7:13,15
	i. 7:20-21
	j. 8:12-13