The panel will useally be started as part of your Xfce session when you start the Xfce desktop enviroment by using the startxfce4 script or a login manager. If you want to start the panel by hand, you can run the xfce4-panel command.
When the panel is started for the first time it will give you the following three options:
This option will try only be available when an old 4.6 panel configuration is found on your system. It will try to migrate the old panel layout to the new panel configuration in Xfconf.
This will import the default panel configuration with most of the default panel plugins. If you use the Xfce 面板 for the first time, this will be a good base to create your own panel configuration.
This will give you one empty panel window. Might be what you want if you have already used Xfce 面板 before and you know what you want.
Once you have choosen the configuration you want, the settings are imported and the panel will show up, for example the default configuration in the picture below. Read more about changing the configuration of the panel and the various plugins in the other sections of this manual.