Thats because it is hard.
Personally I started with a 2x2, this teaches you how to do the corners.
Then try doing the edges of a 3x3.
When you can do each of these things reliably try and do them in a row (corners first then edges)
The more you do it the easier it will become, firstly through familiarity with the letters which correspond to the locations and secondly because you will gain memorisation experience for the letter pairs.