Beta coefficient,in terms of finance and investing,describes how the expected return of a stock or portfoliois correlated to the return of the market as a whole.
So my question is how will I calculate beta of any company stock,say,reliance?

That calculation is probably more geared to a statistics or programmer person than an investor. Beta is widely available on many stock research sites, so there is no need for an investor to calculate it. I suspect most investors are like me when it comes to advanced mathematical formulas. Why would I want to expend the effort when I can find the answer faster than I can input the data to calculate it!

But to get an answer to your question: You might try posting your question under the computer: programming or Science: mathematics categories, or Homework help. Or get a book on statistics. Or do a web search for "how to calculate beta." I'm certain the answer is out there.

Actually, post it in either finance or, prefereably, under homework help for finance and accounting. It uses regression analysis, which is statistics, but it's a finance topic. You could try both places, but as walt says, your average investor doesn't know how to calculate it, only how to utilize the answer (and maybe not even that).

Don't know if you'll have better luck on the homework help. Some of the same people hang around both places.