What part about createunit are you stuck on? Have you succeeded in creating any units? If not, try putting a game logic called someplace, a unit with initialization "alpha = group this", and execute
"SoldierEB" createunit [getpos someplace, alpha]
in a script somewhere.
If you need the name of the cow vehicle type, consult the documentation for MiG Animals. Or, place a cow unit, save mission, and look at mission.sqm to see what was placed. The relevant entry should look like this:
class Item3
{
position[]={5152.100586,16.334999,3999.496094};
azimut=270.000000;
special="NONE";
id=9;
side="WEST";
vehicle="SoldierWB";
rank="CORPORAL";
skill=1.000000;
};
Except that vehicle="SoldierWB" will say something else.