How to save a session manually?

[Wolfgang Mueller]

By invoking "Configure Desktop" and selecting
"Startup and Shutdown" -> "Desktop Session" -> "On Login",
the following list of options is displayed:

   o Restore previous session
   o Restore manually saved session
   o Start with an empty session

Having selected "Restore manually saved session", I do not know how 
to save a session manually. Can somebody help me?

Thank you in advance and best regards,
Wolfgang