To add your company Ranks, go to Company Setup>Organization>Organizational Structure>Ranks.  Here, you can add the various ranks that exist in your company.

Click Add Rank.  The Add Ranks box will pop up.  Enter the name of your rank and its description.  Click Add.

You can now assign the rank you created to your employees.  Click here for more information.  In addition, leave entitlements and tardiness rules are assigned to ranks.