Working off that, you consult a chart that matches the terrain - for example, a road going through forest would give you:
3-4 Woodland (or Road if civilized encounter)
I'll have a set of terrain charts at some point.
Finally you roll 2d10 and take the lower, to give you an encounter. Here's how to use this on the fly.
The top entry in the encounter is the approximate distance in 5 mile hexes from lair (L = always in lair; 0 = 1d6-1 miles away; 1 = 1d10-1 miles away; 2 = 1d20-2 miles away) and time of day the encounter is active (ignore an inappropriate encounter unless you have found the creature's lair). This means you will almost never stumble across a creature's lair by chance.
An X here is a being without a lair; a T means the creature will only be encountered in its native terrain. This last one is more relevant for the hexmap stocking and encounter method I've described before.
The top bold number is the number of creatures in the lair, and the non-bolded number below it is the number of creatures in the encounter. Obviously the number encountered is a maximum for the number in lair. A roman numeral (III, V, X) refers to the number of standard beings you have to have for each higher-level leader-type to exist, and these go up in a pyramid of two (that is, with two basic leaders you get an even higher level leader and so forth).
A "Settle" lair means the beings can be traced to a settlement in range, or if you have not mapped any settlement, a small community of fewer than 100 people.
Some unusual encounters: Homesteaders are just farmers; Wanderers are gypsies, tramps, refugees, or your world's equivalent; Hermits are clerics of that level on a d20 roll of 1-10 and just eccentrics on 11-20; substitute froglings, rabbit people or whatever if you hate halflings; Trickster animals are from my Varlets and Vermin collection; Swanmays and Selkies are from Monster Manual 2 but quite traditional benevolent shapechangers.
I'll let you know when the new silhouettes are added to the zipped download file. Fairly pleased with my werewolf, werebear (based on some long-legged prehistoric bearoid), doppleganger (somewhat distorted from a public domain chupacabra) and swanmay.