I have check this page.. but i do not know..what is "cboproject" and $project.

And how would I know what "cboproject" and $project are?

I have a dropdownbox whose name is "org" and i have to select a value "bacillus anthracis " from it". how to proceed?Plz help me!! Plz help me!!

Try advice from Re: HTML::Form Submit Issue, that's how most of us do scraping. See also Re^7: Perl Mechanize - Header Help required. and Re: Deciphering POST response recorded by HTTP::Recorder for other fine points.