Watch the Adding the Fingers online guitar lesson by Muriel Anderson from 1-2-3 Fingerstyle Guitar
There are lots of ways to make music on the guitar. I'll use some of the more efficient techniques here, to make it easier for you.
Most of the time we'll keep the thriee right hand fingers index, middle and ring, close to the top three strings. That way if you are striking with the index finger you know you'll be playing the third string and when you strike with the ring finger you'll know you'll be playing the first string. (Note, I will refer to right-handed technique in this course, if you are playing a left-handed guitar, just reverse R and L notes.)
Keeping the right hand as relaxed as possible is key in getting a good sound.