Better foods for weight loss?

Hello

So, recently I've been trying to get back on track with working out and eating right. I got after track after some family issues, transitioning to college and a death, and sort of went back to using food for comfort during those sorts of problems and transitions happened. I just decided the other day that I was going to get back to what I was doing before and working out more. After talking with my brother, I realized how important it was for me to start eating better.
I really only eat one meal a day and feel full rather quickly (which is apparently because I don't eat much to begin with and I'm the slowest eater in the history of slowest eaters haha).

I don't want to "diet" because in the past, it never worked for me, and I just ended up being too hard on myself and gave up. I'm trying to just make better choices (like choosing fruits instead of chips or candy at school).

My problem is that I don't really know what to eat (as crazy as that sounds).
I'm not sure what makes a good breakfast, lunch or dinner.
So far, my meals usually consist of a small ham and cheese wrap, fruit, a drink...and that's it. Of course, I snack during the day haha though never on anything good for me.

The thing that makes it even harder is that I'm at school from 9AM to 8PM every Monday and Wendsday, so I'm not sure what exactly to eat for lunch and dinner there that could be more healthy :o My college doesn't have a huge meal selection. Just the basics for hungry college students to feel satisfied haha I've thought about bringing my own food, but like I said, I have no idea what to eat D:

I was also wondering are nutritional bars okay to eat? My brother says use it as a pre-workout snack, but I was wondering if it could help with cravings or be something I snack on during the day until lunch or dinner? :o
The reason I ask is because I used to drink these nutritional shakes (mainly for the flavor), until I saw that they were used to help maintain or gain weight (which I found out is why grandma had them -- to help my great grandma keep her weight). Do nutritional bars do the same thing?