How to upload file in a test through Open Windows using Selenium with Selenium::Remote::Driver package for Perl

In title important part of my issue.I add u additional clarifications : I can get my "button" with following code :

 $elem = $driver->find_element('//*[@id="file_uploader"]/div/div/div/div[1]/div[1]/div/span');
     $driver->mouse_move_to_location(element => $elem); # xoffset => x, yoffset => y
     $driver->click_ok('LEFT');
     $driver->pause(3000);

But after i can't get anything in Open Windows which appears . How is it possible to upload file also in, test ?

How to upload file in a test through Open Windows using Selenium with Selenium::Remote::Driver package for Perl

Many thanks in advance !!