Leaders are a great tool for guiding a reader's eye across a page. Leaders are lines that connect one column to another. A dot leader is one of the more common types of leaders because it is less obtrusive than a solid line. You could create a dot leader by pressing the period key repeatedly until you got to the correct length; however, getting the columns to line up perfectly would be difficult, and your leader would not change if you change your paragraph. A better way is to use InDesign's tab panel to add leaders of any character to tab stops.
Select the text if you are adding the leader to text that is already typed; otherwise position the cursor at the beginning of the text frame.
Click on the "Type" menu and select "Tabs."
Click inside the "Leader" text box.
Type "." (period) or any other character for your leader.
Click in the area directly above the tab ruler to set the tabs.
Position the cursor prior to the tab stop with the leader. Press the "Tab" key.