Note that I've only ever supervised in Australian universities, and different institutions will do things differently - this advice is really for my students.
You've now been enrolled, have a general idea of the project you're working on, and have met your supervisors. What next?
One thing to remember is that a research degree is a long road, and won’t always be easy - but nothing worthwhile ever is. The important thing is to have fun along the way and enjoy learning and discovering new things. Remember your supervisors are here to help in any way we can, but it really is all up to you - and in the end, you’ll have done something truly significant that you can be proud of.
A research degree is very different from other types of studying. From the start of your schooling and throughout your undergraduate degree you've been doing a form of study where everything is short-term. You have a specific assignment or exam to work towards and get regular feedback on how you're progressing. That doesn't happen in a research degree. It will be years before you submit your thesis, and you won't really have any feedback until the examiner reports come back. Of course, you'll get regular feedback from supervisors, so you really have to learn to trust us, because that's pretty much all you get (though see the section about publishing below).
At the start of the degree, your main job is to refine your research topic. This will involve reviewing the current literature to find a clear gap. Once you've discovered the gap, your job is to update your research proposal to clearly specify what the gap is, why it's important for it to be filled, and your plan for filling it. This will allow you to breeze through confirmation, though will constantly need to be updated throughout the rest of your candidature (this is research - if we knew exactly what we were doing right from the start, it would have already been done).