I want to simply block a webpage. I'm using Firefox. This may be simple, but I could use a little help. Thanks.

When you say "block" do you mean to restrict access to it completely.
If so the easiest way is to adjust your hosts file, located in Windows/system32/drivers/etc, with this simple line

127.0.0.1 whatever.com

This will stop access to the site completely, whatever browser you use.

All right, would that number be the same no matter what the site is?
And how excatly do I open up the hosts file to adjust it? With what program?

Are there any alternative ways?

Yes, that IP address is a loop back so it would be the same. Your hosts files is a plain text file that can be edited in Nootepad.

Thank you. Worked just fine.
I appreciate it