Futures are a contract that match up a buyer and seller at a specific price, with the buyer agreeing to pay that price for the asset when the contract expires in the future. The seller is agreeing to deliver the asset, like oil for example, to the buyer when the contract expires. Day traders are never required to deliver or pay for the actual asset, because all positions are opened and closed within the day (no open obligations). Profits are losses are based on the prices the contract is opened and closed at.
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.