Hi,
I have used Wordpress & Drupal and adding themes was just about uploading a theme which I have, since I am new to Plone, can anyone please help if the themes work the same way like they do in Drupal by just uploading a custom theme templates.
Essentially, yes. A Plone theme can be uploaded to a site as a zip file and activated through the web. In fact, with some effort, WordPress or Drupal themes can be used for Plone sites. For more information, see the first four chapters of our theming training.