The format that is generated by parsing is described in the sentence representation page.
Here is a working example usage:
(use-modules (opencog) (opencog exec)) (use-modules (opencog nlp) (opencog nlp lg-parse)) (cog-execute! (LgParseLink (PhraseNode "this is a test.") (LgDictNode "en") (NumberNode 1))) (cog-prt-atomspace)