ok ok sorry.
Right: What Christian gave you was a subroutine, or a function that doesn't 'return' anything. It just does something, in this case it writes out the file to the screen, and tidies up after itself.
Why did he use a subroutine? Because he might want to do it more than once, with different files. So using this method all he has to do is say
<%
ReadDisplayFile("content.txt"

%>
(Note the inverted commas) and it will go to the subroutine and do the code, looking at what's in the brackets. You leave the subroutine code alone. All you have to worry about is having the subroutine code in there, and writing the code to call the subroutine.
ie what I wrote above.
I have no idea what the path to the file is to be honest but it looks like christian's code takes care of it. I would put the file in the same folder as your script and hope for the best. I always used to have to put absolute paths to the document: i think someone else would have to help you with that if it causes trouble.
so in summary:
<% @language="vbscript" %>
<%
ReadDisplayFIle("path-to-document"
SUB ReadDisplayFile(FileToRead)
dim whichfile, fs, thisfile, tempSTR
whichfile=server.mappath(FileToRead)
Set fs = CreateObject("Scripting.FileSystemObject"

Set thisfile = fs.OpenTextFile(whichfile, 1, False)
tempSTR=thisfile.readall
response.write tempSTR
thisfile.Close
set thisfile=nothing
set fs=nothing
END SUB
%>