Pick a game. There are dozens of different video-poker games in casinos. Different games will have different rate of returns, meaning some games, if you win, will give you a higher percentage of your money back and others will give you a lower percentage. A "9/6 Jacks or Better" paytable is the best because the rate of return is 99.54%, meaning the casino only keeps .46% of your money.[1] 

Video Poker is based on the game of draw poker and has virtually the same rules except that you are not playing against any other players. The machine deals five cards on the screen. The player then has the option of drawing up to five new cards. (In some instances you may not want to draw any new cards) You keep the cards you want to keep by pushing the “hold” button that corresponds to the card on the screen. When you have made your choice you hit the “deal” button and the cards you discarded will be replaced by new cards. Your win or loss is determined by the outcome after of your final hand after you hit the draw button. How much you win is based on the pay table that is posted on the front of the machine. 

A straight is a hand with consecutive ranks, like 9? 7? 10? 8? 6?.  Notice again that the cards don't have to appear in order.  The order of face cards, from lowest to highest, is Jack, Queen, King, Ace, which we abbreviate J, Q, K, A.  An ace can also count as 1, to complete a straight where the other cards are 2, 3, 4, and 5.  But it can't count as both a low and a high card, e.g., Q K A 2 3.