The tic-tac-toe tutorial provided on the React website is a good way to get familiar with the basics of React. The tutorial starts out simple and then introduces different concepts until you have built a fully functional application.
Complete the tic-tac-toe tutorial. Note that the tutorial uses codesandbox.io instead of CodePen. You will need to create an account there in order to save your fork of the project. Don't worry about following the tutorial exactly. Feel free to take things in whatever direction interests you. The point is to experiment and have fun.
If your section of this course requires that you submit assignments for grading: Submit your CodeSandbox URL to the Canvas assignment.