I've installed Wowza Media Streaming Server 4 on Windows.
But when I try to open Wowza Manager using "http://localhost:8088/enginemanager" following error is shown in webpage. Please help me what I'm missing or what configuration is needed for Apache Tomcat server.
As you're on Windows it will run as a service if the default installation options were selected. You can also follow the instructions in the link above to run the Manager in stand-alone mode - after ensuring it is stopped as a Windows service. This will show any startup errors in a terminal window and may point to the reason.