Start by placing your ring finger on the 2nd fret of the 2nd string...
.
0
2
0
x
x
x

Individually pick the 1st, 2nd, and 3rd string one at a time, to make sure they ring out clearly!!!

When they do, add the next finger (middle) to the 2nd fret of the 3rd string...

0
2
2
0
x
x

Again, repeat the process of picking each string individually. Make REAL-TIME adjustments to your hand, thumb, and finger position until you can play all the notes totally clear.

Repeat this whole process with your index finger on the 2nd fret of the 4th string.

0
2
2
2
0
x

Once you've done that, you got an A chord! :D