To gain weight, you need to be in a calorie surplus of your BMR. In general the 250-500 calorie range is best per day.
To maintain weight, you should eat very near the exact number of calories you burn each day. A little bit over or under will not make a big difference.
These are all approximates. They may need to be adjusted depending on the individual. Play around with your own macros and total calories until you find the method which gets you results.