Hello HelenaR,

You could use following steps for same.

To edit a file called filename, type nano filename.
Insert new text(which is I guess

Code:

#!bin/ksh 
chmod +x Input_file

) at the current cursor position just by typing the text in.

^O save contents without exiting (you will be prompted for a file to save to)
^X exit nano (you will be prompted to save your file if you haven't)
^T when saving a file, opens a browser that allows you to select a file name from a list of files and directories.

Hope this helps you.

Thanks,
R. Singh