[CentOS] Try KDE Plasma Workspaces

I installed KDE Plasma Workspaces on centos 7 in virtualbox.  I didn't find in any settings panel or during login a way to use it.  I googled to see how to use it, but there are some that say do this but then someone says no do this (editing some files).  I've used some linux distros that allow you to choose during login which to use.  Since I don't see it at login after a reboot, is there a gui or a file to edit to allow me to try it?

Thanks,

-wes