modifying the grid

i'm looking to add a very few specific features to the grid.

i suppose my question is, how can i detect if a particular cell is being clicked?
so far i can only figure out how to display the first cell's information in a row when the row is clicked,r egardless of which cell i'm actually clicking.

i also need a way to address and modify the data within particular cells in the grid, which shouldn't be hard once i can figure out

there are more questions i have, for instance, how to enable just selecting a portion of a row, or to change the background color of cells on the fly ...

if there is any guidance or information you can provide me, i would be greatly indebted to you.

thanks for your time