Ok the 2ed rules should have comp but basicaly its:
Ok your army can include as many hordes as you like. Hordes give access to the following, x4 troop formations (the smallest formations) 1 warmachine, 1 hero AND 1 monster.
For every regiment you take you get access to the following, 1 warmachine or 1 monster or 1 hero.
Horde= 10 frontage x 4 ranks. 40 figures. (think 20 mm x 20mm bases like GW) For large infantry six figures (4mm x 40mm) 3 frontage 2 ranks.
Regiment= 5 x 4 (think again for 20mm x20mm base sizes GW) so 20 figures.
Cavalry are on 25mm x 50mm rectangles (again like GW)
troop = 5
regiment = 10 (5 frontage x 2 rank)
Horde = 20 ( ten frontage x 2 ranks)
large cavalry can be on a 50mm x 50mm or 50mm x 100mm (depending on what thier stat line notes say)
Chariots are on 50mm x 100mm
large creaturtures 50mm x 100mm or 50 x 50mm)
It explains in the rule better than I can here. I could show you in person what it would look like. ONe thing to remember is that there are no casualty removals in KOW. The formations or Units take wounds until they waver or break. ONce break happens the whole unit is pulled from the table. The actual foot print of the unit is what is important here but the figure count less so. For instance say you wanted to have a horde of human shield wall from the Kingdom of Man army. 40 figures right? Not exactly. Say you wanted to model it with 30 figures and make a cool little diorama. You could glue the 30 figure diorama on 200mm x 80mm movement tray. It would have the same foot print as a horde but used with less figures.
Clear as mud?http://www.manticgames.com/free-rules.html
Page three and towar the end should answer any questions as well. There are also some free army lists as well. Keep in mind the complete army lists will be in the rule book. But each list has enough units to make things interesting. For you having historical figures may I suggest using the kingdom of man lists?