Select the exam and if you have approved accommodations, check the box "Use Accommodations" to practice with time or display adjustments.
You will then go through a practice exam including all sections - Listening and Reading, a short break, then Writing and Speaking. It is not scored - this is just to practice taking the exam in the digital format.
Everything is timed so if you don't see an option to move on, look for a clock in the top right corner to see when you can.
Notice the dropdown keyboard options on the writing portions as the default may not be your preference.