To maintain weight simply don't eat more calories than you need

A typical active adult needs about 2000 calories a day, maybe up to 2400 if you have a very physical job or might only be 1800 a day if you sit behind a desk

To know if you are eating right, the rules are simple:

If you gain weight you are eating too much so cut back

If you are losing weight (and you don't want to) then you are not eating enough

And if your weight is stable you are eating exactly what you need....