Hi Zill, it's great that you've taken steps to restart your studies. It can feel intimidating after a long break but there are some tips on the ACCA website on how to kickstart your journey to qualification - click here to access.
Before you attempt your first computer-based exam, the best thing you can do to prepare is use the ACCA Practice Platform. This resource allows you to practice questions in exam-like conditions. You'll be able to familiarise yourself with interface and exam format - this will hopefully increase confidence ahead of the real thing. Find out more here.
Best of luck - do reach out to the community for support throughout your studies :)