I'm working on SharePoint search.
I'm trying to edit search page, because I have to configure refiner.
The reason for this is I have added enterprise keyword column to add in keywords. However when I search in a keyword it pick up in the search. But not in left hand side column.
Please suggest some solution
This page is not intended to be changed. It is a system page, changing it would change the query for everyone in every site collection. The best practice it to avoid it all together by routing your queries to the Search Center. You can do this through the site collection Search settings. Ref:Article
But you can use Custom Refinement Panel on OSSSearchResults.aspx
you can create a custom page and add search result web parts and refiners
Steps to create custom page and assigning it as search page. https://chayadigital.wordpress.com/2011/06/30/how-to-create-a-custom-search-page-in-sharepoint-2010-publishing-sites/
Steps to add refinement filter https://blogs.technet.microsoft.com/tothesharepoint/2013/11/10/how-to-add-refiners-to-your-search-results-page-in-sharepoint-2013/
Since you are on SharePoint online, things will work slightly differently if you want to create refiners. Two in particular:
1) You will need to wait for the crawl to index or force document library (under settings) to reindex. 2) Mapping properties (you can't create your own) to RefineableString0X. Have a look at this short video (also explaining how t edit the search page through search centre)
