Start from the top down. IF I'm correct it's a 4x5 square.
xxxxx<--- this row first
xxxxx<--- Next
xxlxxx Now when you get to the bottom 2 rows, do this.
xxlxxx Divide them in half like that, and do the left box of 4 first. Then when you've finished that do the right box of 6. If it's 5x5, then just do the same thing but add a row before the bottom 2.
Good luck.