The rules of UNO are simple. The remainder of the deck is placed face down to form a draw pile. And the top card of the draw pile is turned over to start a discard pile. The person to the left of the dealer starts play and has to match the card on the discard pile, either by number or colour.
The object is simple get rid of all your cards before everyone else. Match the number, colour, or type of card to play; use a wild if you don't have a match, or draw from the pile until you get a card you can play.