|Version of ServletExec||URL to use|
|5.0 or higher||http://<hostName>/servletexec/admin|
|4.2 or older||http://<hostName>/servlet/admin|
In addition, if you installed SE on a windows machine then you could just go:
Start - Programs - New Atlanta - ServletExec - ServletExec Admin
The URL to use to access the Main SE admin UI is also documented in the SE User Guide (which comes with your installed version of SE, in the "Documentation" folder).