FileDialog and ProgressBar

I want to do something like below in Java : I have an applet, when I click a button in the applet,
it will generate something....while waiting for the process, I will pop up a Jdialog which contain the
progress bar showing the progress of the applet process..now the problem is, how do I check the excution time in applet ? how will I know how many percent left to complete the process ?

how do I do that ??

another question is, if I want to invoke a FileDialog in an applet, how do i do that (my applet is a signed applet).....the problem is, applet is not a windows based object...when i want to instantiate a FileDialog, I have to tell the FileDialog the parent which call it... how to do that ?

thanks
thanks for ur help ...