Question about Cloud

Hello,

I am new to Cloud and have a question.

I have a spring based web application which I have developed and deployed on Weblogic. Now if I want to deploy this application on the Cloud with provider providing me 'n' weblogic servers on the fly.

Say - I want to pay for the weblogic and database space only as I need.

If 100 users are there - Cloud should consist 1 weblogic server and as the load increases I want the application to be distributed on multiple instances of weblogic servers which increase the available instances for my application.

How do we achieve this solution?

If this is possible, what is the best architecture for the requirement?