These directions are for making a copy of a report using ServiceNow's Classic UI. If you are working in the new UI in ServiceNow Kingston, please see ServiceNow Reports (Kingston UI): Make a Copy of a Report. You can make a copy of an existing report so that you can make then modify it for your own needs.
Find and run the report you'd like to copy.
Rename the report by changing or replacing the text in the title.
Most of the time you will be making the current report yours by replacing the word Template with your Internet ID.
If you are changing something specific about the report in any meaningful way make sure the title appropriately reflects the content AND remember to end your title with your Internet ID.
Once the name has been changed, click the down arrow to the right of the Save button and select Insert and Stay.
You have now copied a report and can modify it for your own needs.