by Dai_trying » 2019-09-10 06:25
Debian boot menu in those instruction refers to the grub menu, although it is difficult to offer more assistance with vague comments like "the commands I typed weren't recognized. " it would be better to post here the exact command you used and the exact response you received.
I could guess that you maybe don't have sudo installed in which case you would need to make yourself root first (su -) and then use the commands from those instructions without "sudo".
Another guess could be that you are not using Xfce as I was for those instructions and therefore you might need to stop (and later start) a different unit.
If you could let us know which desktop version (Gnome, Xfce, Lxde, Plasma or other) you are using it might be a start...