LearnPython.org provides a series of self-guided tutorials for familiarizing yourself with basic Python concepts, syntax, and operations.
You can spend the afternoon session working through these lessons on your own if you want more practice. Mentors will be nearby and ready to help with any questions you might have!
If you would like to run through the same lessons in Jupyter Notebooks rather than on LearnPython.org, you can download notebooks for each of the "Learn the Basics" lessons here. Run them on your computer by unzipping the file, placing the .ipynb files on your desktop, and opening them in Jupyter!