The next verse makes it clear that we are dealing with a burnt offering.
On the sabbath day: two male lambs a year old without blemish, and two-tenths of an ephah of choice flour for a grain offering, mixed with oil, and its drink offering— this is the burnt offering for every sabbath, in addition to the regular burnt offering and its drink offering. (28:9-10 NRSV)
Accordingly, the law of Leviticus 1:10-13 applies:
If your gift for a burnt offering is from the flock, from the sheep or goats, your offering shall be a male without blemish. It shall be slaughtered on the north side of the altar before the Lord, and Aaron’s sons the priests shall dash its blood against all sides of the altar. It shall be cut up into its parts, with its head and its suet, and the priest shall arrange them on the wood that is on the fire on the altar; but the entrails and the legs shall be washed with water. Then the priest shall offer the whole and turn it into smoke on the altar; it is a burnt offering, an offering by fire of pleasing odor to the Lord.
As to when it was offered, rabbinic tradition puts it after the morning continual offering and before the evening continual offering (Mishnah Zevachim 10:1; BT Pesachim 58b). Otherwise, the text itself offers no time other than saying that it was offered on the sabbath.