manual input into editable cells

Hi,
I have set up a grid with data from a MySQL database and can get it to write back to the database afterward. What I am having a problem with is updating my onscreen totals and the cell formatting. Now I know after reading hundreds of postings that I have to code my own update. What I need to know is how to setoff the trigger. ie. onchange, onmouseup. I am right in assuming that I can use these and if so where do I put them? I have seen some example of formating cells, but they don't work with manually entered data.

Any help please