This installation steps are applicable for the OpenCart versions 1.5.x.x

Installation via File Manager or Filezilla

1. You will find upload folder inside for for opencart 1.5.x.x folder
2. Copy or drag the contents inside the upload folder to your web root directory such that the admin folder merges with the existing admin folder.
3. Login to website admin
4. Go to Extensions > Modules
5. Look for ORDER ID SETUP (Lite) in the modules list and click on Install.
6. Edit the module and setup.