You'll need to reach out to your Tableau Account Manager to find out if your Tableau Online site has been set up. Once it is, you'll get an email notifications with instructions on how to access your Tableau Online site.
Thank you Carisa. I tried reaching out to my Account Manager via firect email and support team. He didn't even acknowledge my email :-( ..Strange experience. The new subscription scheme is very confusing for esisting customers and the account manager refuses to reply. Never expected this from tableau.
Many Thanks to you for replying to me