goto the 'movie' menu and down to 'get movie properties'
select 'video track' on the left side of the pop up menu that appears
then on select 'size' on the right hand side of that menu
you can then rotate, adjust size etc. with the buttons on the bottom of that menu and preview in the main window
in the 'file' menu select 'export' and choose the file format, codec etc that you want.