Lets start by knowing why the sky is blue right now. About 70% of our atmosphere is nitrogen, which reflects blue light. If the sky was green, the chemical composition would be different, most likely consisting of gas chlorine because that is the most common green gas element. If the sky was green and 70% of our atmosphere was chlorine, then life on earth would be very different. instead of containing some nitrogen, we would contain chlorine, which is actually poisonous for us right now. Life wouldve evolved differently. We wouldnt have amino acids, which have nitrogen, but rather some molecule of the sort to store genetic information. Photosynthetic organisms like algae, grass, and trees would be red-orange or purpleish because they need to absorb the green light that comes from the sky. large bodies of water would be greenish and look pretty gross.The sunset would look yellowish redish greenish. The rest is really up to you to decide :P