Premier help

I am trying to expand the whole movie with the size of 720x576 to fill up the whole movie screen but i have no idea why i cant.
a screenshot of what i am trying to say is attached to this thread.
the one in the monitor window is the movie that i imported but after some editing, i want to export it with its size exactly the same. however whenever i export, it exports the movie shown in the sqeuence window which seems to be like resized a little and with the black borders at the two sides(originally i made it to be just 2 black borders on the top and bottom).
how do i make it so that everything will be original like what i had before but with the things that i edited in adobe premier of course.