Choose 'New Notebook' or open an nb file.

Note the prompt. The session activity will be saved automatically as an unnamed file.

It may be convenient to name the file. Enter the file name in the box and click the -button.

In[...] for input code and Out[...] for its result. The following code is modification of the original code by Miyadera and Fukui (宮寺 & 福井、数式処理 26, No. 2, 3-23 (2020)).

Let's add frame and color background to the table above. See also my technical note (in Japanese).