How to create, load and save files in Mu

You need to understand what each of the following three buttons do:

New - Click on this button to create a new empty file. Before you can run your code you’ll need to save it (i.e. give it a filename).
Load - When you click this button a file selector dialog box pops up and you should click on the Python file you’d like to load into Mu (or press cancel).
Save - Clicking this button saves the file in the currently selected tab. If the file was newly created then Mu will ask you for a name for the file.

Copy/Rename Files

If you want to create a newly named copy of the current file you can rename it by clicking on the filename in the file's tab in Mu.

Don't Use Python Module Names

It's tempting to name your new file that uses the turtle module as "turtle.py". Don't do this! If you name your file after a module you're using in your code then Python will break because it's trying to import your code rather than the code from Python's standard library!