#1: Landscape orientation works best for these types of shots 99% of the time. As-is, there is a lot of useless foreground that is also highlighted by flash.
#2: One of the things you will begin to learn is the difference between photography and snapshots. While the viewer can see and appreciate that you were trying to capture a beautiful sunset, there is also a trash can prominently featured here, in addition to random people. Sunset photos are a dime a dozen, so in order for them to stand out, you must learn to pay attention to details like this in order to set your photos apart from the pack.