The words "for themselves" are a metonym for what they will do with the high places. AT: "built for their own use" (See: [[rc://en/ta/man/translate/figs-metonymy]]and [[rc://en/ta/man/translate/figs-rpronouns]])
# on every high hill and under every green tree
This is likely tobe an exaggeration that indicates there were many places like these for false worship all over the country. AT: "on the high hills and under the green trees" (See: [[rc://en/ta/man/translate/figs-hyperbole]])