I edited the file that was created specific to the VPN server I was using.
After you navigate to the file as described in your post, type at the prompt:
sudo nano filename
"filename" will be that file name specific to the VPN server that was created. Change my generic "filename" to your specific filename. My VPN uses alot of servers in various places and I have to modify each Terminal file created if I want to use them.
After you type that, you will be prompted for your password. I type in the password and press enter. Then I press enter again and the file appears using the editor app "nano".
To the left of my Terminal screen near the bottom there are control keys that include an option to use "nano" specific keys. The option menu appears as three rows of horizontal short dashes stacked on each other. Press this, and while holding it down, slide your finger on the screen to select "nano" at the top. This will give you the control keys you can use for nano. I just use the control-x key to save and eventually exit. Follow the directions on the screen after your selections. It was described elsewhere that you cannot use your VPN editor to make changes after you save the Terminal file because it will write over the file and you have to start over. I did the VPN editor setup first, then the Terminal file mod and it has worked fine so far. You can use your finger on the screen to control the cursor. It took a little practice for me to get it right.