The cool thing about playing the guitar is that you can skip over a lot of the fundamentals and jump right in to playing chords. The fundamental chords utilize all four fingers and all six guitar strings.
I found a cool video on You Tube that explains how to play the 4 most commonly used chords in many popular forms of music.
This video focuses on the G chord, the C9 Chord, Em7, and D. As the video explains the finger positioning on the strings is relatively similar on all of these chords and they provide a good foundation for building up your finger strength and strumming technique.
Watch the video as Aaron Tomberlin explains in more detail. I hope this helps.