oops...
www.daphile.comfor linux you need to navigate to the directory:
cd /boot/
to list the dir content type
ls -alh
if config.txt is there you can type
vi config.txt
this will edit the file using the built in VI editor program.
Using VI is not a trivial task mind you....
step one, navigate to spot you want to edit with your arrows,
then hit the letter a to change from command mode to insert mode
then make the changes, hit ESC to go back to command mode.
then press :
and type wq
(write and quit)
After reboot it should run the edited config.txt file