Hi agrawalatul,
you may use the Standard Image & Files uploads plugin to attahce images and files to the events, also as I think you intend to use this feature as a minute for each event, you may use the Agenda & minutes plugin to relate each past event with a Joomla! article. This way you can enhance your presentation of these minutes.

Both plugins are available to Silver and Gold members

thanks for the reply. Please also let us know if there is a demo available for these plugins.

I have seen a demo of standard images and file upload plugins. They seems to be more associated with putting the impages in the file and that too a small number. We are looking for uploading event pictures (after the event) and uploading them to the event. The user should be able to see this pictures or an album of the same post the event.

Then probably Agenda and minutes plugin is best suited to your needs. With that you can allow your users in the frontend of your site to create an article with all your images and link it to the event.