On the ruler there are certain symbols indicating the margins and the tabs that you have entered. The left edge indicates two arrows for the left margin, and the first line indentation. The right edge indicates one arrow for the right margin. By clicking on the tab bar, you can enter your own tab stops where the cursor is placed. You select the tab types using the shortcut buttons on the button row.
You can move the margin arrows left or right, using your mouse. You can move them in millimeter intervals.
Example 1: First line indentation.
Example 2: Hanging indentation.