Say you need to create a table similar to the existing one. You can copy any created table and adjust it according to your needs.
Click the Setup link in the top right corner of the window.
Select the Database tab.
From the setup menu select Tables > Customize existing tables. The system will display a list of tables that already exist :
Click on the Copy button next to the necessary table to create a new table with the same fields
If you need to copy data, select the Copy Data option.
Please note that all relations created in the original table will be created in the copy of this table automatically.
Next: Changing Tables Order