Start with some simple commands
Just like dogs (don't let Fluffy hear that), cats begin obedience training with the "sit" command.
Put your cat on a table and pet her so she's comfortable.
Say, "Kitty, sit" (only say your cat's name instead of "kitty"). As you do, move the training spoon with the food over your cat's head. Your cat will tip its head back to follow the food, and its body will naturally move into the seated position. When that happens, click the clicker, say "good sit," and give her a lick of food.
Repeat until your cat automatically responds to the command.
It's OK to gently guide your cat's rear to the table if your cat isn't getting the hang of it. But do not push on your cat's back. You could hurt her, or she might become stubborn and refuse to do what you want.
Say "Kitty, come!" (again, use your cat's own name) to your cat when he's within hearing distance. Click the clicker two to three times. The food on the training tool should bring your cat running.
When your cat comes, click the clicker again, praise him, and give him some of the food on the spoon.
Repeat from a different spot in the room.
Eventually, your cat will come on command, and all you'll have to do is click the clicker and -of course - have a treat ready.