Good BNF grammar tutorial / introduction for a beginner?

What's your tip for an introduction to BNF grammar (and how to use them in practice)?

Something concise with many examples would be great. Have been googling but only found enormously long artcles with unclear examples so far :/

(In my particular case, I'm trying to parse the Galaxy Toolconfig syntax, which includes if/else s开发者_StackOverflow中文版tatements etc.)

i've always found the abnf rfc very good when regarding these issues: http://www.ietf.org/rfc/rfc2234.txt