Step 1 : Enable Search Service application / if not we need to create the Search Service Application
Step 2 : Goto SharePoint central admin -> Application Management ->Manage Services on Server.
Step 3 : Start the “SharePoint Server Search” by clicking Start at the right side.
Step 4 : Click Manage service application under Application Management will display a list of Service applications.
Step 5 : Click New Search service application in the ribbon.
Step 6 : Give a Service application Name and click OK will create a new search service application.
Step 7 : Next the Search service application will be configured.
Step 8 : Click on the content source on the right side to configure it
Step 9: Click on the Edit for the Local SharePoint Sites and add the Site URL in the following rectangular space with each site in a separate new line.
Step 10: Please configure an Incremental crawl and a full crawl.