Well the way I designed the app is with Arrays. So the grid of letters is stored in a variable like "A,D,C,D,F,X,G,S" etc. Then it's dumped into an array using the tokenat expression to split it up. Same goes for the Words and the Keys.
My vb app just generates those strings after my grid is built. Hopefully that makes sense. A lot of times when working on projects it helpful to build a Level Editor, or something like this that just helps. I didn't do it with my first word search game and it took much longer to build the levels :). Now I can easily make more levels to offer and sell :).