There are two ways to add a favourite competition. It works the same way on Android and iOS. (There are videos of both below)
The first way is to use the search function to find the competition.
Press the search button at the bottom, write in the name of the competition, press on it and then press the star.
If you want to add notifications, click on where it says notifications and then choose to use the default option or press customise to choose custom notifications.
The second way is to go into the calendar and then press edit in top right-hand corner.
From there you can search for the competition you want to add and then click on it. It will then be added to you followed competitions.
If you want to add notifications, you need to find it in the list of your competitions, press on it and then select Notifications.