Checks for empty fields and resets focus to the missing textbox.
Sets cursor to first textbox onLoad.
Used two forms to make it easier to clear the text boxes (while missing the buttons). Couldve probably accomplished this w/ one form if i would have used a hard reload (location.reload()) instead of setting each txtfield to ""

Did not address out-of-bounds errors. Also did not check to see if the entry was a number as opposed to a text string, although the latter will not cause any errors, but merely no answer.