How to search a string and return it's range? [resolved]

i am not sure how to use the activecell.find="text", however, i did try a small testing on it. and it doesn't seem to work. (or maybe i didi it wrong in teh beginning.)

anyway, wat i want is to search a string "A234DF" from a selected column (not by row, e.g. Column A) then return it's range such as "A10" is where it stores "A234DF".

i was also trying to use the "For...next" fucntion to loop every cell and search teh correct ones. but i don't know how to define the "Max" count for the cell, how can it stop looping if i don't know how to get the maximum value (the last item's position) of the column.

any help for me?