A lot of apps don’t have icons. It’s simple.
Open the /Applications folder; right-click on the app you’re discussing, and click “Get info.” Left-click the icon at the top-left of the “Get info” window, next to the app’s name, once: it will become selected and display a blue border. Hit ⌘C.
Open /Developer/Applications/Utilities/Icon Composer.app; hit ⌘V. Save the file with ⌘S.
Open the resultant .icns file with Preview.app. Use File > Save As… to export the file as a .png (with alpha-layer!)
Upload that .png to the app’s page here on RoaringApps.