When there is a notification or multiple notifications for you in 1Rink, you can view them by clicking on the bell icon in the top left corner.  There will also be a number with the number of notifications that haven’t been acknowledged yet since the last time you opened your notifications:

Clicking on this icon will open your Notifications menu with all notifications available to you:

To mark a notification as seen, you can either click on each individual notification to open and view it, or you can mark all notifications as seen by clicking on the eye icon:

You will be met with a pop-up that you can answer either “Yes” or “No” to either mark all notifications as seen or not:

Doing this will clear all notifications that have not been read yet.