how to edit .bashrc file (GUI?)

I wanted to upgrade my mothur from 1.34.4 to 1.39 in linux.

after installation of latest mothur, only the older version was working.

So based on the instructions from mothur installation wiki, i changed the path of the older version, however I am not able to open the new mothur in all folder locations.

I found instructions to edit path in .bashrc, but i am not sure how to open bashrc in gui because it says permission denied to open it from the hidden file folders in ‘Home’ directory. and I am not sure how to edit the path in command prompt…

Could some one kindly give me detailed instructions on how to edit the .bashrc file so that I could use my mothur in any folder location.

I am relatively new to linux. I would appreciate any help.

Thank you