Congratulations Joyeeta on securing an endorsement! :)
I believe the correct link for Stage 2 of the process is given on this page, depending on whether you are present inside or outside of the UK: https://www.gov.uk/tier-1-exceptional-talent/apply
I want to add, your circumstances will dictate what follows: a new BRP or not, biometrics, etc. The next steps become clearer as you proceed with the Stage 2 process.