Updating a plugin
If the new version of already installed plugin appears on the market, just visit the market from admin panel and install that plugin over again. New version will be installed automatically. Plugin author decides how the update is handled and how database migrations are done. It works exactly the same as the manual update described below.
To manually update a plugin, you need to deactivate a plugin, then update its files, and activate a plugin again.
To do this, go to Plugin administration page, click on a plugin tab, and click Deactivate button.
Then, delete your plugin files from Plugin directory. Copy updated plugin files.
Finally, activate your updated plugin again by clicking Activate button.