You can add an object to a panel in several ways, as follows:
From the panel popup menu
Right-click on a vacant space on a panel to open the panel popup menu. The panel popup menu contains an Add to Panel submenu. The Add to Panel submenu enables you to add the following objects to your panels:
Accessory applets
Amusement applets
Internet applets
Multimedia applets
Utility applets
Launchers
Launchers from menus
GNOME Menu
Drawers
Log Out button
Lock button
From any menu
When you right-click on a launcher in any menu, a popup menu for the launcher opens. You can use this popup menu to add the launcher to a panel.
You can also drag menus, launchers, and applets from menus to panels.
From the file manager
Each launcher and applet corresponds to a .desktop file. You can drag the .desktop file on to your panels to add the launcher or applet to the panel.
Each menu corresponds to a directory. You can drag the directory on to your panels to add the directory to the panel as a menu object.