Chords are learned with the help of a chord diagram. This will show you exactly where to place your left hand fingers in order to play a particular chord. A chord diagram is a grid of horizontal and vertical lines representing the strings and frets of the guitar.
The black dots show you where to place your left hand fingers. The white number tells you which finger to press on the string just behind the fret. If there is no dot on a string, you play it as an open (not fretted) string.