You can't really learn the art of interpreting art because interpreting art is just how you see the art and what you think the art means and is trying to say. Everyone has their own way seeing things and everyone has their own way of taking that in. So the art of interpreting art would just be to be able to see the meaning of art how you see it but also as the artist saw it, what emotions he/she was experiencing and what motivated them to create the piece.
When interpreting the meaning of art you usually look at the colors- if there are dull colors they were usually a bit depressed and if you have ever see dull colored work it often makes you feel a bit depressed as well. This does not mean the painting is bad, it is just another form of art. If the colors are bright the artist was usually happy, even excited sometimes. When I'm excited I usually go a bit crazy and if I was an artist I would go a bit crazy with bright colors as well.(article from Helium)