We want what we want and we want it now. (Humans are better than most animals at deferring gratification, but not always and not by much.) Any deliberate manipulation of another creature's behavior requires that we become attuned to that creature's desires, and these may be almost as idiosyncratic among dogs or dolphins as among people. To paraphrase Sam the Eagle (of Muppet Caper fame), we are all weirdos. This is where behaviorism goes productively amok.
In operant conditioning, one doesn't create behavior per se, one merely increases or decreases the likelihood that a given behavior will be performed, and one does this by controlling the behavior's consequence.
Consequences fall into four categories, defined by two binary oppositions (positive/negative, reinforcement/punishment): positive reinforcement, negative reinforcement, positive punishment, and negative punishment. "Positive" in this context refers to the addition of some thing or force, "negative" to the removal of some thing or force. "Reinforcement" names anything that increases the likelihood that a behavior will be repeated; "punishment" names anything that decreases that likelihood. More simply, reinforcement tends to the yummy and pleasing, punishment to the nasty and fearsome ("aversive" in behaviorist lingo).
So "positive reinforcement" is the introduction of something good (chocolate cake, a belly rub, a game of tug, a shoulder massage), "negative reinforcement" the removal of something bad (pressure on the bit, a parent's screaming, a scary dog or mailman): whatever I did to create either consequence, I'm more likely to repeat it. "Positive punishment," which sounds like a contradiction in terms, is the introduction of something nasty (leash jerk, skunk spray, burned fingers), while "negative punishment" is the removal of something we like (attention, bones, freedom): whatever I did to earn these consequences, I'd like to avoid repeating it.
There's a wealth of complications buried in this simple schema, but the most significant concerns the vagaries of desire. We all (human and non-human animals) like different things, and we like them with varying degrees of intensity. Our desires are fluid and changeable, shifting with experience, mood, and context. Once upon a time, I loved bananas and (very briefly) the voice of Suzanne Vega, but both now make me queasy. Conditioning wouldn't be possible if our preferences were forever fixed, but our fickleness makes us slippery subjects. And that seems very much to the good. I have learned to love Skinner only because his account of behavior remains forever incomplete; the "laws" of behaviorism, while they are powerfully, empirically predictive in the aggregate, get wonderfully complicated when they tangle with the rebelliously singular individual.