How do I access Celestia?

Could you please explain the process of accessing Celestia? I'm interested in exploring this platform but am not quite sure how to proceed. Could you outline the steps involved in gaining access? Also, are there any specific requirements or prerequisites that I need to fulfill before I can start using Celestia? Additionally, is there a user-friendly interface or tutorial available to help me navigate the platform easily? Thank you for your assistance in this matter.