When a user goes to your website with an exported project on it, the project is downloaded and run locally on that user's computer. Each visitor to the website gets their own copy. These copies do not talk to each other or your website/host, unless specifically made to. Any data entered and stored is stored locally on each user's device.
You can "send" information outside of your app by using the 'post to url' action via the AJAX object (or possibly the multiplayer plugin, websocket plugin, or other 3rd party database plugin).
In general, having multiple copies of your app communicate with each other and keeping persistent data will require knowledge and use of some outside server to manage the data. If you don't require persistent data across sessions the built in multiplayer plugin might be sufficient.