The following chord diagrams represent the first 4 frets of a 5-string banjo tuned (G D G B D)
The number indicates which finger you should use (1=index finger, 2=middle finger, etc.)
A lowercase "m" denotes a minor chord (Em = E minor)
These chord shapes are arranged in order of difficulty.
If you want to learn triads, inversions, and how to play ANY chord then check out Winston Style.
If you're just starting out, check out Ready To Roll and learn all the basics.