Click on each sprite to do things. Remember to make sure your pet isn't hungry or bored. To make the pet full click the fish and to make the pet not bored click the drums or the ball. Also, you can try clicking the penguin itself.
I clicked on the 'Tips' bar at the top of the Scratch web page and followed the steps on the 'Virtual Pet' one. I will try to share every day unless I am working on a massive release of a game or piece of art or anything like that.