about swap memory and desktops

[srer]

I have a swap partition on my disk but have no swap memory after installation. Maybe it's because I didn't install it during installation. The question is that can I add it now without installing the whole system again?

The second question is that I found there is a field on the left side of the login screen to let me choose which desktop manager to use. So does it mean that I can install more than one desktop in one system? If the answer is yes, then how to add another desktop to the system? I am using KDE now.

[Anaximandar]

Yes, it is possible to mount the swap partition with the command #swapon . If the partition is not created, can be created using $diskdrake .
You can use other desktop environments at the same time.
For example, you can install LxQt environment adding package task-lxqt .

Kind regards