What date format was this file I downloaded in

For the first part of your question, "What file should the command go in?": put the command in ~/.bash_profile using your favorite editor. For example, you can do this using nano by opening Terminal and typing

nano .bash_profile

Type in the command and then press ctrl+X to exit. Say yes, you want to save the file.

For the second part, "Is there anything else I should know?": You are also going to need to install bcat, a program which allows you to send text to a browser via the command line. You can do this by running

sudo gem install bcat

in the terminal and entering your password.

Now you can view man pages in your browser by typing bman. For example:

bman ls

1. Check with Terminal to see if what the permissions are set to.
2. Do Command + I to get info on the file, then check the file extension. Also check to see if the default "Open With:" drop down box is set to TextEdit.