How am I supposed to make my new living room look good? bright green carpet?!?

Any chance there are wood floors under it? Pull up a corner in the closet if any have that carpeting running into it. I'd pull it up (even though it's new) if wood floors were an option. Even if they may be a bit rough, put some some nice neutral area rugs to define seating and dining areas. If the carpet must stay, I'd go very neutral on the walls. Very light beige tones if you want beige or off-white, antique white. Tans and browns on the walls may make it look "lodgy" with that color green. However, if smartly decorated, the floor color won't be as noticeable. Work with the green in your accessories. Do lots of different shades of green, sages, etc that all work well together to get a cohesive look. Such as in artwork, pillows, etc.