Hi Yang Fan,
Probably you have at the root of the source folder a file named package.xml and a folder with the content of the widget. You should zip these two and give the file an mpk extension instead of zip, like “MyWidget.mpk”.
If you put that mpk-file in your widget folder (overwrite existing one if you update), then you can click Synchronize Project Directory in the Studio Pro (Shortcut: F4).
You then have updated the widget! If the configuration fields changed, you will see an error and have to update also the usages of the widget.
Hope this helps!