This is the way to play an open A minor chord: see how the tip of the fingers fret the strings at about a right angle. The thumb is jutting out from the neck and helps the grip and the wrist is on the same line as the forearm. Again, if you're not playing Classical guitar, there are no fixed rules: your thumb may be behind the neck or the palm could wrap around it with the thumb sticking out even more. The important thing is that the fingers fret the strings in a way that produces a good sound. If possible, keep your fingers close to the fret on your right (looking down) like the index and ring finger in Fig. 1: this is where the sound is produced, not where you put your finger and the closer to the fret the easier it is to press down the string and get a clean tone.
Keeping your finger at a right angle to the fretboard makes it also easier to fret just the string you're supposed to without touching the one below and producing unwanted buzzs and noises or, worse still, muting the string altogether.
From your point of view (Fig. 2), you should see the forearm and the hand on the same line: this ensures the maximum spread for your fingers. The muscles and tendons that move your finger are actually in your forearm (if you practice too much or don't warm up properly, that's where you'll feel the strain) so bending your wrist sideways will shorten some of the muscles and limit the movement of the relative fingers.
In Fig. 3 you can see how the palm of the hand is not touching the back of the neck and the wrist is not turned inwards: this is another position that shortens the muscles so avoid it unless you're playing some very simple and easy stuff and you don't need to spread your fingers.