Islamic Republic of Iran Air Force Kowsar is the modified version of F-5E with advanced avionics and fire control system. It is being produced in single-seat and twin-seat variants.
In the zip file, you will find two skins with the difference in the design being in the underbelly.
To install, unzip the .rar file and copy/replace the folders either to:
~\Eagle Dynamics\DCS World OpenBeta\CoreMods\aircraft\F-5E\Liveries\F-5E-3