You don't state whether or not you know anything about
Front Page or that you have been asked by your sister for
help because you know how to spell the word "computer".
I would suggest that you & your sister consult Front Page
help for "publish".
You first have to determine whether or not your sister
created a Front Page web as the first step in devoloping
her web site ... many people who have similar problems do
not. One must do this.
I assume that your sister has contracted the services of
a host for her website. She cannot just simply publish
her website to the WWW.
You next have to determine whether or not the host
supports the Front Page Extensions and has enabled them
on her account. To find out, ask the host. If so use
the "http" method of publishing. If not, you must use
the "FTP" method of publishing. See Front Page help in
either case using the search terms I have put in
quotation marks. If you use the http method, Front Page
will handle the proper file name for the "home" page for
you. If you FTP, check with the host to determine the
proper file name for the home page. It will be something
like index.htm, index.html, default.htm, default.html,
etc.
You must know the URL, Username and Password in order to
publish. You will be prompted for them by Front Page.
Once you have done all of these things, follow the
instructions in Front Page help and give it a try.
If you are still having problems, return here with more
details and any specific error messages you may be
receiving.