The first ten chapters of Numbers describe the organization of the Camp of Israel and Israel's preparations to depart from Mount Sinai. An ideal picture is presented of the camp, which is modeled after God's heavenly camp. Each tribe---indeed, each individual---contributed to the group effort and had a place in the camp. With God in their midst, the camp was to be ritually and morally pure, as taught in Numbers 5-6.
These chapters of Numbers also describe how the Israelites would break camp and travel. The tribes, grouped into four groups of three tribes each, would arrange themselves in a set order. The tribe of Levi was in charge of taking down, transporting, and then setting up the tabernacle in a new location.
The nation would know where and when to travel by following the guidance of the divine Cloud that accompanied them (Nu 9:15-23). More detailed direction would be provided by the priests through signals given by holy silver trumpets.
The camp departed from Sinai early in the second year of the Exodus, on the twentieth day of the second month. Their jubilant and orderly departure is described in Numbers 10, which pictures their travel as a kind of liturgical procession or victory march.
After the beautiful ideal picture of Numbers 1-10, we start to read about the realities of Israel's wilderness journey in Numbers 11. The nation leaves Sinai with the same set of problems which they brought there. Complaints soon begin, then spread and escalate. God, who had dealt patiently with the traumatized former slaves in the early stages of the Exodus, now imposes firmer discipline (Nu 11:1-3).
Moses, who had been looking forward optimistically to Israel's arrival in the Promised Land, is shocked by what transpires. Complaints are growing, putting the Israelites on a course for disaster. He is at a loss to know how he can change the hearts of the people, which is what is needed to put the journey back on track. And so he turns to God, asking for help. He confesses his dilemma and reminds God of his promises and his ultimate responsibility for the project (Nu 11:10-15).