i use a date n time picker it pic the time when aplication is run and not changes

my aplication is window form based. dear i want to use it like digital clock. which will
tell time of entry made because i will save it through file handling in text file.

another problem  i want write selected value of comobox in text file through stream writer

most important is
what kind of application it is web or windows?

For windows you can just use timer control available
and in Web you can achieve it using Timer Control avaiable with Ajax Extensions.
 
Mark this is currect answer if it helped.