Newbie: MatchAllDocsQuery sample?

[Ian Vink]

Is there a simple example on how to query for "contents:Hello" in all
documents using
MatchAllDocsQuery<http://incubator.apache.org/lucene.net/docs/2.1/Lucene.Net.Search.MatchAllDocsQuery.html>
 ?
I want 100% of the docs with "Hello"

Ian