Just follow the instructions for each level, trying to figure out what they mean and then performing the action(s) required. It's a bit like a classic riddle game, but with a large dose of pointing and clicking added to make it accessible to a more casual audience.
The beginning levels seem super easy, and then the difficulty wall comes and you'll be soon scratching your head wondering what the author wants you to do. And that's the real trouble with riddles games (or technical instructions for that matter): trying to get inside the author's head to understand what is expected of you. Some things you see will be clues and have meaning, others will just be filler or a red herring. It's a puzzle game that may not appeal to everyone, but as puzzle games go, this one is wicked fun.