For someone who's 23 your not eating better than the majority your age. But if you want to improve it, you can almost always make better choices. Just take one area at a time and swap it out for something better.

Soda would be the first to cut out, and fresca is still a soda even if it doesnt taste as sweet. Try just water. Cereal can be better replaced with oatmeal, sweetened with maple syrup or fruit. Replace white bread with whole wheat bread, etc.

Anything highly processed is worse for you than something less processed, whole grains better than white, fish better than meat, chicken better than beef, etc. For almost anything your about to eat/drink think if there is a 'better' alternative. Its all stuff i'm sure you already knew.