To add an object to a panel, perform the following steps:
Right-click on a vacant space on a panel to open the panel popup menu.
Choose Add to Panel.
The Add to Panel dialog opens.The available panel objects are listed alphabetically, with launchers at the top.
You can type a part of the name or description of an object in the find box. This will narrow the list to those objects that match what you type.
To restore the full list, delete the text in the find box.
Either drag an object from the list to a panel, or select an object from the list and click Add to add it at the spot on the panel where you first right-clicked.
You can add also add any item in the Applications menu to the panel: right-click the menu item and choose Add this launcher to panel.
Each launcher corresponds to a .desktop file. You can drag a .desktop file on to your panels to add the launcher to the panel.