Here are some important keyboard shortcuts to remember: 
- Click a cell and press Enter to enter edit mode, which allows you to change the contents of a cell. 
- To exit edit mode, press Esc. 
- To execute the contents of a cell, press the Ctrl and Enter buttons at the same time.
The following commands must be entered in command mode.  
- To add a new cell above the current cell, press a. 
- To add a new cell below the current cell, press b. 
- To delete the current cell, press the d key twice. (dd). 
You can view these shortcuts by clicking Help > Keyboard Shortcuts or by clicking the Help tab in the sidebar.