Chords are 3 more notes sounded together.
Major -> Root (first), Third and Perfect 5th of the major scale.
Minor -> Based on the major chord, lower the third note half a step.C major -> C E G
Augmented -> From the major chord, raise the 5th note 1/2 step .C E G -> C E♭ G
Diminished -> Still from major chord, lower the 3rd and 5th 1/2 step.C E G-> C E G♯
Know your scales. Study the major chords. That should get you started.C E G -> C E♭ G♭