Not entirely sure what you are asking. You should be able to go back to the iPad's homescreen from Safari by clicking the home button on the front of the iPad beneath the screen. If you've logged into a particular website on Safari then the site should have a logout/logoff button somewhere on the screen. If you want to close a tab in Safari then tap the '+' on the left-hand end of the tab (you can't close the last tab).
If you mean something else ... ?