You need handle animal(see skills, its all handled there) trick of attack to attack humanoids, animals etc. You need the attack all trick (-edit actually the attack trick twice) to attack more unnatural things like undead and abominations and the like. Combat trained is a catch-all of a few combat themed tricks (including the attack trick but not the attack all trick).
Depending on your class, directing to attack could be a move action or a free action (if you get a mount as an animal companion, the 1st level ability Link allows you to direct as a move action)
You can "push" an animal to make it do a trick it doesnt already know. This requires an full round action (or move action if you have the link ability from animal companio) and the animal performs it on its next turn