The word walk is expounded in Genesis 6 when the author is describing the life of Noah. Verse 9 uses the same word in the same syntax (other than the fact that for Noah it is in the perfect and for Enoch it was in the imperfect) to describe the relationship that Noah had with God. When the two uses are juxtaposed to each other, we understand the relationship that Enoch had with with God. If Noah and Enoch were both said to have walked with God, then we know the following about Enoch since more is said regarding Noah:
Enoch was a "righteous" man
Enoch was "blameless" among the people of his time
Enoch found "favor" in the eyes of the LORD.
I still need to stay right here for a little bit. This adds a little more light to the life of Noah's grandfather.