Using GPG key from website

[McCullough, Chad {D106~Indianapolis}]

Hello,

I'm new to using encryption and have a question that I couldn't find an
answer to in the how-to's and FAQ.  When someone posts their gpg key on
a website, how would I import that key so I can use it to send that user
an email?  Is it as simple as copying and pasting it somewhere?  I'm not
sure if this matters, but I'm running Kmail on a Linux and FreeBSD box.
I'm also wondering how I would do this on a Windows box?  My parents are
using Windows XP and I would like to have them use encryption, as well,
when needed.   

Thanks for the help.
Chad