Visual Equation is expected to be user-friendly and intuitive, so it should not be difficult to use if you understand its usage. Basically:

Instead of a cursor, you navigate with a "ghost" that surrounds blocks of the equation, from single symbols to arguments, operators and the entire equation. Change the ghost's selection and insert characters at the direction in which the ghost is facing by pressing keys on the keyboard or clicking symbols in the bottom panel. If the ghost surrounds a square, as when you open the program, you overwrite the square.

These are the main keys:

You may learn also the short-cuts noted in the menu.