Hi sukimac
use the returning command to get the values you tryed to update after the update. it works like this

update table_name
set column_name = X
returning column_name [into v_x];

dbms_output.put_line(v_x);

this works only if you update one row at a time! if not, it will not work!!!

you can also use sql%rowcount to count how many lines you updated

if you have more problems, show us a print out of the trigger