Begin your quest of mastering the backhand loop by first learning the backhand drive, the backhand chop and the backhand smash. You should have a repertoire of strokes depending on how the ball is returned to you. The whole set of games should be compared as the melody of a song. The backhand loop is just a note in that melody.
A mistake that most beginners make is to come to the club with a friend and then spend the whole night playing against the same player. To improve rapidly, you have to play against a few players of different playing styles. Observe how your opponent executes the loop. It is a good idea to choose an opponent whose playing strength is just slightly more than yours. Try hard to beat him. Get another friend to video-tape that game. Study the game afterward, to see if you had been making mistakes or mis-judgement. Apply what you had learnt in your next game.
You can also learn by watching table tennis videos. You have to watch one video several times before you can get the feel of the whole game. Again, try to apply what you had learnt to your next game. Obviously, those professionals playing in the video make everything look so simple.
Next, do not forget that there is a wealth of information to be gained by reading books. To be a well-rounded player, you have to master all the strokes that make up the beautiful game of table tennis.