To open the code editor click the 'c' key on your keyboard. It should bring up a popup on half of your screen.
If you are using an iPad, look for the small icon on the top of your screen that looks like a robot face. When you click on that it should bring you to the code editor.
Now that we've picked the correct editor. Let's open up a new project. Click on the plus button to add one. If you worked on code last week you might see what you worked on last time.
It's always good to know what code does just from the name of the file. Naming our code something like "farm challenge" or "obstacle course" is a good way to keep track of it.