After you update all tasks which are in progress with the Actual Start date etc -- you should move any incomplete work forward to the status date through Tools > Tracking Update Project > Reschedule Uncompleted work to start after (Project 2007).

and how about uncompleted work started in the past and it was supposed to be finished in the past but didnt finish? in primavera when i updated the dateline, it automatically used to add to the duration and shift the task to the right, making it longer duration. Here how is that done?

That is precisely what Tools > Tracking Update Project > Reschedule Uncompleted work to start after command does.