Did you run the biblatex command? The .bib file must first be turned into a .bbl with the references formatted according to the style. You also have to run latex multiple times, in each pass it resolves missing references from previous passes.

How do i run the biblatex command?.

I saw that Jabref jhas made both .bib and .bbl files with same name. Kindly help me in this regard

Hmm, in case you use an IDE like WinEdt, the program should also take care of your references. You could check the latex log for errors, I guess that the editor does not find your bbl file.

I never used WinEdt, maybe you have to add/register the bib file in your project so that it is used for ref generation.

You are correct the .bbl file ls created but ls empty with entries in the .blb file only. How do l add those entries to .bbl file?

Maybe this helps:

http://www.andy-roberts.net/writing/latex/bibliographies

Did you set a bib style? Maybe it does not succeed to generate a .bbl without it.

\bibliographystyle{plain}

\bibliography{sample}

Please show a minimal working example of your code, so we can have a look at it. At the moment its just shooting into the dark. If your problem can not be solved here, I would recommend moving over to tex.stackexchange (https://tex.stackexchange.com/) where a lot of real experienced users are present.

First of all, you don't need to add manually

\section{References}

as a new section is automatically generated (as long as you are with article class). The problem of [?] is very well know and extensively described in http://tex.stackexchange.com/a/63875/13304

Most often, and I think it is your case, that problem is due to a missing run of bibtex. Since you're using WinEdit, you may consider to run PDFTeXify (see http://www.winedt.com/snap.html) which is a sort of quick build. Basically, it runs pdflatex and all other routines for bibliographies, glossaries and indexes.