The first thing to do : SAVE THE FILE !
First you must create a directory where to save your scene. You can save
it in "c:\rted\Scenes\edtut1\" directory. You must create it with File
manager or explorer or other programs. Then from menu "File" select "Save
As...". A Dialog box will pop up.
Select the directory, then choose a file name which finishes with ".rt".
You can choose "edtut1.rt".
Press OK button.
Now you have created the scene file. On the title of the window you
should see this: