You may be using something similar to clicker training already without realizing it. Do you say "Good dog" after your dog does something you like? In clicker training, that's called a marker. Often it's a brief, easily-recognized sound that tells your dog they have done something you like.
And generally, you follow that marker with something your dog likes, right? Like food or praise or petting. In clicker training, that's called a reinforcer.
Clicker training includes three steps:
The dog exhibits a behavior you like, such as sitting or coming when you say, "here." When your dog is learning a behavior, you won't say anything; you'll wait for the behavior. You can adjust the environment to make it easy for your dog to succeed and can deliver the reinforcer in a location that encourages the dog to repeat the behavior. For example, if you put a dog bed on the floor, a dog might lie down whether or not you say "lie down." If you toss the reinforcer (in this case, a treat) off the bed, the dog will likely get up to retrieve the treat and then return to the bed, giving you a second opportunity to mark and reinforce the behavior.
You mark the behavior precisely when the dog completes it. Clicker trainers usually use clickers as the marker, but they can use words, sounds, lights, or anything the dog can easily perceive. We like clickers because they're efficient; they sound the same every time and their timing tends to be more precise than verbal markers. When a clicker isn't handy, you can make a sound. I recommend one that you don't use in any other setting, such as "bip." The marker communicates that your dog has demonstrated a behavior you like, and your dog has earned a reinforcer.
You deliver a reinforcer, usually a treat, but it can also be a toy, touch, or praise. The key is choosing something your dog really likes. It has to be valuable enough to make your dog want to exhibit the behavior again and again. Think about it this way, if you studied for a chemistry exam and aced it, would you be happy if your friends or family reinforced you with a bowl of shredded wheat? Make sure that the reinforcer matches your dog's efforts.