You shouldn't need to do anything if it's a standard Relate site. Have you tried creating a blog and search for that?
I've just created a blog which I could use for testing the search functionality. And right on the Search button, I searched for test, freedom, countrymen and it just doesn't produce any results.
You can test it yourself if you must.
It doesn't work for some reason and I have no idea why because this is a default install.
I suggest you enable EPiServer error logging and check the log file. You will see the search service requests produced. I assume you have the search service installed in the same application in which case you should see requests to /IndexingService/IndexingService.svc (you might have to enable logging at the debug level)
You can try to browse to /IndexingService/IndexingService.svc where you should see a WCF service "endpoint not found" message. If that works, try to browse to the URL found in the log (/IndexingService/IndexingService.svc followed by some more or less long querystring). That can give more clues to what is wrong. It should return an atom document (xml).
I've set up a new Relate+ site. I created a user named user1.
I then tried searching user1 from the search bar on top but I didn't get any results.
Do I need to configure anything first before the search functionality starts to work?
Thanks.