Trending stocks rarely move in a straight line, but instead in a step-like pattern. For example, a stock might go up for several days, followed by a few steps back during the next few days before heading north again. If several of these zig-zag patterns are strung together, and the chart appears to be moving higher with some degree of predictability, the stock is said to be in an uptrend.
In addition to knowledge of basic trading procedures, day traders need to keep up on the latest stock market news and events that affect stocks—the Fed's interest rate plans, the economic outlook, etc. So do your homework. Make a wish list of stocks you'd like to trade and keep yourself informed about the selected companies and general markets. Scan business news and visit reliable financial websites.