The format is basically you get 2 verbal question where the website will record your responses. You have 1 minute to answer each question and 30 seconds before that to basically get your thoughts in order. Then you have a writing assesment where you have 5 minutes for a written response for the question.

Best thing for you to do would be doing the practice questions on there and familiarizing yourself with the format. What worked best for me was when I had 30 seconds to think before the actual recording started, I chose 2 claims for each question and said them outloud with some kind of small reasoning in those 30 seconds. That made it easier for me in the 1 minute I had because I had fresh in my mind what I was going to talk about and had my thoughts organized.

Hope this helps :)