Can't edit startup when I copied a disk file onto it.

Hi. I've just written a keycard/password program and it uses two computers so I wrote it on one and tried to use a disk and copy it onto the other. So I copied it onto the computer and when I try to edit it it says "Cannot edit a directory." The program runs when I reboot the computer and it works fine on the first computer I wrote it on. Can someone help me?

Edit: Re-wrote the program, don't worry.

For the future, you can simply upload it to pastebin using the computer.
To do this you do:
pastebin put FIILENAME (to upload)
pastebin get CODE FILE (code being the code for pastebin, the code will given when you put the file to pastebin, file being the name that it will save as)

Or…

(Works on Single player or if you are hosting a server)
You can go to your saves folder and navigate to the "computer" folder in which will be a list of ID's of all the computers in that world, find the ID which has the code and copy it to the other computer you want it on.

what happens when you do this on the computer with the error?

cd startup