You can either create a seek to find an opponent or you can select an open seek from another member.
Do you want to play live or daily games?
Are you playing on an app or the website?
The easiest/quickest way is to click on the "play" icon (the pawn with a hand), then select either "Live Chess" or "Daily Chess":
Select your time control, then click on "Play" and wait for a match up.