For use plugin add code to your view:
<?php $groupDocs = new GroupDocsViewer_GroupDocs(); ?>
<?php echo $groupDocs->renderFrame(); ?>For configure default params login as admin and go to "Extras" => "Configure GroupDocs Viewer" menu.
Also you can override default params like:
<?php $groupDocs1 = new GroupDocsViewer_GroupDocs(array( 'fileid' => '123', 'frameborder' => '1', 'width' => '680', 'height' => '900' )); ?>
<?php echo $groupDocs1->renderFrame(); ?>