If you have jd.sh placed in opt, unpack attached file with 7-zip and then place jdownloader.desktop file in /usr/share/applications/hildon/ and icon jdownloader.png in /home/opt/usr/share/icons/hicolor/64x64/apps/. If you have jd.sh somewhere else then just edit "Exec's" path in jdownloader.desktop file with text editor (leafpad, nano...).