i think i understand where the error were in the script (only wild guessing)

1.)triple '*' because, the first '*' is for pointer intializing and the other two for the two-dimensions

2.) i forgot the brackets: (myString[x])[y] = str_create("TEST_");

do i have to put everytime these brackets around my array, if i assign a variable?
thanks alot that helped me, but don't ask me, why this additional brackets have to be. i think you know it better. and yes studing some books about should help :-)