geez, ok just typing the filename from a command prompt wont do squat-------it may try to execute the filename as though its a program, but it isnt gonna open it
in order to open a text file you use an editor, try pico or vi or whatever editors you have installed, have no clue whats on your machine, pico is part of the pine package, you will find vi very very confusing at first but its the standard text editor installed on most systems, pico is much easier to use
this isnt a permissions issue, this is lack of understanding of what the **** your doing
assuming your running a GUI there are numerous text editors available that are much easier to use, try one of those
who owns public_html/mdlabs/draw_triangle ? all of it, each directory? If all this is in your home directory which it appears to be, and they were created by the same user and NOT root, none of this should be happening-------- using ls -l from in a directory will list all the files with size and permissions ----you will see a bunch of rwxrwxrwx type stuff on the left, r=read w=write x=execute, one column for root, one for user, and one for owner I believe
little tip, suppose you want to open hypotenuse.html and edit it, if you have pico available and installed, type pico mdlabs/dra(tab key)/hyp(tab key) -------tab key will autocomplete file names or directories or commands for you or show whatever options or commands are available when you hit the tab key a couple times
do some reading up on BASH and commandline skills, although similar to DOS, its much more powerful with alot more options