"First blood" offline Heroes 4 tournament

I don't quite understand this rule... You can't split an army... for example, into one or more simple units (send a single wolf for scouting). Does there have to be a hero in the unit? And can an army from a castle not be moved to the main hero without a (secondary hero...) meaning, can archangels not be sent on a journey... Please explain... I want to play by the rules, otherwise I might pass... waste time... and it would be disappointing... ;)