A char is not a string. Consequently, you cannot manipulate it with functions designed to take strings. Furthermore, you can't just tack it on with myString [strlen (myString)] = myChar, because you have to follow it with the '\0' char. Either take both those steps, or make your variable a string instead of a char.
The thing is, you have to deal with things as they are designed to work, not as you WISH they worked. That means reading the function docs carefully as well as learning the differences between chars and strings and pointers and arrays.