Links to pages that may help you to learn how to use parse:
Red specific links:
http://www.red-by-example.org/parse.html - Maybe the best resource available.
http://www.red-lang.org/2013/11/041-introducing-parse.html
http://www.michaelsydenham.com/reds-parse-dialect/
https://github.com/red/red/issues/3478 - Not what you expect, but informative anyway. Discusses issues of parse.
The following links refer to Parse in Rebol :
http://video.respectech.com - with interactive editor.
http://www.rebol.com/docs/core23/rebolcore-15.html
http://www.codeconscious.com/rebol/parse-tutorial.html
http://www.codeconscious.com/rebol/r2-to-r3-parse.html
http://www.rebol.com/r3/docs/concepts/parsing-summary.html - very informative.
http://www.rebol.com/r3/docs/functions/parse.html
http://blog.hostilefork.com/why-rebol-red-parse-cool/
https://en.wikibooks.org/wiki/Rebol_Programming/Language_Features/Parse/Parse_expressions
http://rebol2.blogspot.com/2012/05/text-extraction-with-parse.html
https://github.com/revault/rebol-wiki/wiki/Parse-Project
http://www.colellachiara.com/soft/Misc/parse-rep.html - proposals for improvements of parse