First install and "turn on" crontab.
sudo apt update
sudo apt install cron
sudo systemctl enable cron
crontab -e
Then choose an editor:
Select an editor. To change later, run 'select-editor'.
1. /bin/nano
2. /usr/bin/vim.basic <--- most familiar
3. /usr/bin/vim.tiny
4. /bin/ed
Choose 1-4 [1]:
I chose option 2 because I'm familiar with vim.
Then, to do something every hour:
0 * * * * python3 ~/path/to/script.py