If you plan on playing jugle, you're in luck. Everything between the three lanes is yours. Although, be weary of crossing the river because that's where the enemy jungler will be spending most of his time. As for you, you have your own side of the river.

One Important thing to note is after a cycle through all the jungle camps, you may use the river to gank but it is a hot spot. especially once dragons and rift monsters spawn.

During the first 30 second of the game, you will be waiting for minions and monsters to spawn. The pictures shown are where a jungler would usually wait as to not waste time doing a full camp clear.

CS means combat score, and you gain cs by killing minions or monsters. CS only counts by killing, not damaging, because an ally champion can steal the kill. Yes even in jungle. CS will grant you gold. You can think of CS as last-hitting a monster for the gold. Otherwise it will be wasted and no one, or someone else, gets the gold. You want that gold because it your only source of income as a jungler.