The first group that you will learn about are the mortals of chaos. The troops are very good, a lot better then human warriors, orc warriors, and elfin warriors all together.  They get strong weapons, very good armor, and very powerful mounts. A chaos mortal army is a very strong army and a good one for beginners to start with. also they get some very good magical spells to get fid of the war machines that may come in your way.

 
 
the history of the mortal chaos follower all starts after the north and polar gates collapsed and the raw magical chaotic energy was pushed back to the north and south. when the first men began to appear in the old world. some of them when north, so far north that they discovered the realm of chaos, a zone filled with pure magic and the four chaos gods, Khorne, Nurgle, tzeentch, and Slaanesh.  
 
so lets look at some of the advantages of a mortal chaos army. their troops are very strong and are armed with good weapons to help them take out their enemies. the lord ( if equipped right) are strong enough to take out a small army easily. they get great mounts like a daemonic mount, like a juggernaut of Khorne, a steed of Slaanesh, a disk of Tzeentch, or even a mighty two headed dragon of chaos!
  but with most advantages there are some disadvantages. the main one is that besides the magic, all of the chaos armies don't have any kind of firepower like bows or guns. plus they get no war machines like stone throwers or bolt throwers or canons! but other then that a mortal chaos army can be a powerful one if played right.     
to deamons to chaos to beast