Excell how do I hide/protect columns

I clicked on HELP within Excel and searched for "Hide Cells "

Display or hide all values in a cell
Select the cells that contain hidden values or values you want to hide.
On the Format menu, click Cells, and then click the Number tab.
Do one of the following:
Display hidden values in a cell

In the Category list, click General to apply the default number format.

To redisplay a date, a time, or values that have a specific number format, select the appropriate date, time, or number format on the Number tab.

Hide all values in a cell

In the Category list, click Custom.
In the Type box, select the existing codes and press BACKSPACE.
In the Type box, type ;;; (three semicolons).