At last i have found a compatible software for my project. would someone help me how to create external links on omeka page, what plugins to use for image slider and rating of posts or images.

Where, exactly, do you want to create links? In item descriptions, on a simple page, as part of the navigation?

oh thanks for responding to this. in item descriptions or alternatively on simple page. thanks once again.

In both instances you should be able to tick the "Use HTML Editor" or "Use HTML" option (its own line in Simple Pages, below an input field in elements). That will add a WYSIWYG editor.