Hi Jim,
Thank you for your kind support,
Please let me know whether I need to upload the catalog folder to modules folder or should I upload the files in the catalog folder (admin, EXT, Images,includes,index.php) into the modules folder. (I am getting confused in this part).
As my installation is a fresh one, I believe that I just need to as stated above.
I have installed Oscommerce in my root folder of my website.