During the turn based game, you'll be able to play against one of your friends or against a random opponent. Once you've chosen your language and opponent, the game will start.
Then, you'll see the different categories and you'll have to choose one of them. By doing so, you'll receive the card with the word you'll have to draw. If you don't want to or don't know how to draw what the card says, you'll be able to replace it for another one in exchange for coins or pencils, depending on the situation. The option to do so will appear at the bottom left of the screen. Otherwise, choose "Play" and start drawing.
Remember that there is no time limit to draw in this type of game, therefore, you can get as inspired as you want to help the other player guess correctly. Once the drawing is finished, you'll have to send it by tapping on the top right corner of the screen.