You go on finviz.com under screener and then the fan technical. From there you choose beta under 1.0 from there you can choose the stocks you want to trade.
Beta is indicating the correlation to the stock market; a low beta is not necessarily synonymous to low volatility. Volatility is the standard deviation of returns, and can be calculated as such, assuming that past volatility is largely correlated with future volatility. This textbook calculation suffers from lag. Possible improvements to the lag can be made using are ATR over short periods, or Yang-Zhang volatility. Cheers, Felix