A clicker is used to mark a behaviour rather than digging through pockets and bags to get treats as the behaviour has to be rewarded the second they do it. Start by just clicking it and then giving him a treat straight after so he learns that the click means he gets a treat. Then when he does a desired behaviour click and give him a treat this way he can learn some really good behaviours very quickly. The first few times just click and treat and then once he's learned that behaviour gets him a click build in the word or hand signal.