Learn the ten basic, five-card hands of poker: (1) "Royal flush" or called "Ace-high straight flush"), (2) "Straight flush", (3) "Four of a kind", (4) "Full house", (5) "Flush", (6) "Straight", (7) "Three of a kind", (8) "Two pair", (9) "Pair", (10) "High card".
See also the "Poker Hands: Reference Sheet" -- a list of poker hands described in detail with examples and color pictures of hands in a subsection above the "Tips" section near the bottom of the article.
Learn the basics of poker using 5-card hands. Using the standard 4-suits (clubs, diamonds, hearts and spades in no order or rank), 52-card deck with or without jokers/wild-cards, etc. -- so there are many variations of games agreed upon before the first card is dealt. For example, the ace normally plays high, but you can sometimes agree: "aces high and low" (to be used as either the highest or the "one-card" in the hand, otherwise 2 is the low card). A joker or other wild card(s) may be agreed upon. At the end of each hand there can be a showdown if more than one has not folded/discarded or mucked cards, if so then those players still remaining in that one hand compare their cards according to the hand rankings and card values (explained below). "Suited" (of a certain suit) cards are not used to break ties but if all 5 cards are of one, same suit (a flush) that beats the "unsuited" hand, nor are cards beyond the fifth (don't draw to break the tie); only the best five cards in each hand are used in the comparison. In the case of a tie, the pot is split equally among the tied-winning hands.
Wild cards introduce an additional hand, "five of a kind," which normally ranks between a "straight flush" and the Royal Flush (ace-high straight-flush). When a joker is in play, it usually can only be used as (1) an ace or to (2) complete a straight or flush as needed. So, it is not used as a true wild card for any and every hand.
Print or write out a ranking of the poker hands and memorize the hands. Become familiar with the names and meanings of poker hands and their variations by value of cards that form it (like a pair of Ks beats a pair of Qs or lower). The person who wins is the person with the highest-valued hand. You can't win, if you don't know which hand beats another to take the pot. If two players have hands with the same name (e.g. two "full houses" [FH]) or no one has an obviously winning hand, then the player with the highest differing value card in their hand wins (Ace is normally the highest [Ace-high beats King-high]).
Play online. Playing online gives you much more variety of games and skill level. You also get the advantage of leaving whenever you want. If you play online make sure you play at reputable sites.