You pet him. [ Said as if it's self-explanatory. It isn't, though, so he goes on to add. ]

You use your hands to stroke them gently. Some dogs like belly rubs while others prefer ear scratches. But generally they like just about anything. [ As he talks, he shows her how to do it, stroking a hand along the puppy's back, then down to his tummy and chest, finally moving up to his head to scratch him behind his ears. The puppy lets out a satisfied sigh, his eyelids lowering pleasantly as he keeps his eyes fixed on Bruce. ] Like this. See?