Anyway, here's how it works -
If your acrosses and downs match, then that cell letter is confirmed - if they clash, one of those letters is entered correctly for the down, say - but incorrectly for the across. Any letter in an unchecked cell is confirmed.
Now you know that 2d is entered BIKAR, you know that 14ac must be entered LKIRS (so that it has just the one misprint) and so on. But you must be sure each time you confirm a letter, no guesses (or you'll get into a mess)!