There is so much I can write about nutrition but I'll give some simple facts.
Food is good and tasty and we need it everyday. You just have to decide if you want the sugars and processed food that does so much damage to our bodies and make us gain weigh and feel terrible or do we want the good delicious crunchy and nutritious foods that make our bodies feel good and work properly.
I know it's paints such a different pictures. And yet, it's hard. They put things in those bad foods that taste good and make us crave it and want it and then once we've eaten them, they make us feel sluggish and bloated.
So the simple truth is we need fruits and veggies, we need some dairy and lean meats and we even need a little bit of the good fats. The long and the short of it is, that you need to do some research, read labels, find out what your body needs to be healthy and take control of what you put in your body.
Experiment and enjoy finding foods that you like. Watch portion sizes and find out what a proper portion is. You can track calories with a few different websites. I've used two and they are free. If you do a search you can probably find others.