The chance says when you roll. On the Night road table, that is once each hour of travel, and an encounter happens on a 1 in 6.
If the chance hits, roll the table die. A d12 is the Night road die. Faces 5 through 7 are the wolf row.
Read the row type, then do that thing. A note is color. An event is a beat. An NPC, an SRD monster, or a Forge encounter is what you put in front of the party.
Some rows roll again. The wolf row says then 1d4 wolves. The first die picks the row. The second die picks how many.