Firstly you must understand that unlike QTP, Selenium is NOT a test tool. It is just a library to allow automation of a web browser. It does not provide an assertion mechanism, test runner, reporting, etc that commercial tools like QTP do.
Instead, you have to combine Selenium with a test framework library. These are platform specific and will provide you with methods to structure tests, make assertions and create reports.
There are many options such as RSpec (Ruby), Cucumber (Ruby/Java), NUnit (C#), TestNG (Java), and many, many more.