virtualbox.org

does not install as mentioned here:

menu item named "Insert Guest Additions CD image", which mounts the Guest Additions ISO file inside your virtual machine. A Windows guest should then automatically start the Guest Additions installer

actually nothing happens...

suggestions?

If autostart is disabled you will need to manually start the install. Use the file manager and start from the cd.

There is a CD drive but only a few backup files on it CD - nothing else

EDIT: I think I got it:

1) insert GA CD image...
2) Open CD and run GA...

well you have to know that

It is actually all described in the User Manual.