Have you get through with your problem by now?
In Linux there is what we call "permissions" or "authority" to read or write or execute files <like scripts or commands> a regular user may have limited permissions, only "root" has the super user permissions. If you know how to become "root" user in your linux then you can execute any command available or open read write any file in the system.
In linux mint you enter:
$ sudo -i
$ (enter your regular user password)
see your terminal will look like that and you're now a root
but be careful and be sparing in running your pc as root as there are many things you should avoid yourself, remember the saying: WITH GREAT POWER IS GREAT RESPONSIBILITY, you are responsible in whatever you act upon your system as root.
New linux users must read basic tutorials in order to enjoy more in their linux experience. Here is the tutorial, very good tutorial, that helped me in many ways learning linux:
You can download the pdf file into your Desktop so that you can read it or make it a reference even offline. Mint can open pdf files automatically.
Hope this helps. Goodluck.