How to find a ripe melon
You take a piece of straw and lay it crosswise at the widest point of the melon, if the straw rotates so that it aligns with each end the melon is ripe.
Thump the melon solidly with forefinger, if it sounds solid its still green, if it sounds hollow it ripe.
Cut it open, if the all the seeds are black it is ripe, if some of the seeds are white it's still green, and if there are no seeds--guess.