There are a couple of notification plugins depending on your needs.
If you're looking for on-site notifications, you are looking for the plugin On-Site Notifications that is also listed on that list of plugins on the link above
Welcome to the Q&A site for Question2Answer.
If you have a question about Q2A, please ask here, in English.
To report a bug, please create a new issue on Github or ask a question here with the bug tag.
If you just want to try Q2A, please use the demo site.