Combining Column Values Into One Column

Hi Folks, Im new to SQL, and I am trying to do the following:

I have a table Documents with DocID, Path and FileName.
A second table Keywords has KwdID, KeywordString
A third table DocumentKeywords links the two with DocID,KwdID. Multiple keywords are linked to one document.

I want to create a SELECT query that makes a result table that contains Path, FileName and Keywords columns where the Keywords column contains entries like "Keyword1,Keyword2,Keyword3" ie. a comma delimited list of keyword strings which have been built from the keywords that associate with a specific document.

I found a nice sample here
http://www.sqlteam.com/article/using-coalesce-to-build-comma-delimited-string
which shows how to return just the comma delimited string itself:

DECLARE @List varchar(100)

SELECT @List = COALESCE(@List + ', ', '') + Keywords.KeywordString
FROM DocumentKeywords
WHERE KwdID = 1

SELECT @List


I cannot seem to integrate this into the query so that it calculates the string for each row on the fly. My suspicion is that the capability is there. Can somebody point me in the right direction?

Thanks