There is no manual that tells you how to do this.
Sorry not at my CSS comp right now.
But from memory, if your in a server hit “ESC” go to “Options” then “Advance” then “Keyboard” then you need to check the box “Enable Develeper Console”, don’t quote me but I think that’s it.
then to open the console while in game hit the Tilde-key “~” I think that is default to open it.
Then you can type those commands in.
If all else fails there are some small videos on Youtube, search for “how to activate developer console in CSS?” and you should find something.