Here are the default basic functions.
Attack: "O" on PS, "B" on Xbox will throw a punch.
Block: Holding "R2" on PS, RT on Xbox will attempt to block incoming attacks. Timing these can create openings for counter-attacks.
Grab: Pressing the "Triangle" on PS or "Y" on Xbox will attempt to grab or grapple the apponent. While holding them, you can throw or choke them as well.
Dodge: By pressing the "Square" on PS or the "X" on Xbox, while moving the left thumb (LT), you can perform a dodge as well as create openings for more counter-attacks.
There are many combo attacks and using the surrounding objects can help as well (throwing people out windows and up against walls). Keep at it and keep your guard up.