I spent too much time writing this out ·-·; (TL;DR, read words I highlighted in blue only)
I'm by far not a professional chef, but I can cook pretty well.
One of the things that helped me out was cooking soup with whatever we had at the time over and over again.
I like the idea of starting off with cooking soup because 1) You can turn almost anything into soup with enough time and effort. 2) It's a very good and easy way of learning how to mix different flavors and ingredients together to learn how to cook food that you personally enjoy. 3) You have a lot of control over how healthy something is. If it has too many calories in it, you can water it down. Double the water = half the calories per serving. Need protein? Maybe add beans. Need more vegetables? Add vegetables, etc.
For me, I started off with scrambled eggs because it's kind of hard to mess something up that only has one ingredient in it. Then I got into confections, which to be honest was probably a stupid move, but now I know how to sweeten things, properly use flavor extracts, how to properly caramelize, etc... Well that doesn't help me eat, so I started making soup because it's easy. I started off with instant soup broth and noodles. Perfected being able to cook soup with a base already made and juggling that and cooking different types of noodles. Then I started experimenting with things like spices and salt and stuff. Then I kind of just played with that for a long time because now I'm factoring in different ingredients that need to be balanced. Then I started taking ideas from random cook books, seeing what I liked, seeing what I didn't, used spices that I liked and omitted ingredients that I didn't. I wound up with a really good potato soup recipe. Then I started doing more canned stuff and experimenting with vegetables and stuff.
Being into confection I kind of also got into extracting. That isn't exactly the most useful skill in college, but I spend over $800 a year on liquid herbs and extracts so tincturing, extracting, and infusing are pretty useful skills for me.
If you have some sort of thing that would be nice if you could make on your own, it's never too early to start learning that skill.
Controlling nutrition of what you put into soup:
My current diet involves me needing more protein and carbohydrates, so I put beans and more noodles and pasta in my soup than you normally would and keep my water content relatively low so I get more calories per meal. Celery is a great vegetable to add for losing weight.
If you want to avoid carbohydrates and have something healthier use beans instead of pasta. Soup is a great opportunity to mix in liquid supplements and vitamins that you wouldn't normally take. I think vitamin D is one of the easiest vitamins to do that with.
vegetable oil is probably the healthiest alternative you can get for making roux, but ultimately if you need to thicken your soup you'll probably wind up using less flour and fat if you use real butter.
Whether you want to gain weight or lose weight, avoid all trans fats.
Summary of what I suggest:
start with scrambled eggs and basic soups and noodles. Soup broths, maybe experiment with some spices and stuff when you're feeling daring.
Recipes are nice to follow, especially if they work well, but experimenting, trying new things, and completely failing to cook something is one of the best ways to get better.
It's probably safer to experiment with cheap ingredients and save good and more expensive ingredients for an actual recipe.
If something is consistantly working, it's a good idea to write it down. You can't memorize everything you do.
Good ramen resource: College Survival Guide Part I: 50 Amazing Ramen Noodle Recipes