Gym question?

so i’m 16 years old and around 98 pounds and i wanna start gaining muscle as i’ve been going to the gym for about 3 months but i’m unsure about the amount of calories i should eat in a day for me to start gaining muscle, is there a way to find out or???

Are you male or female? And what is your height, and resistance training (e.g. weights) routine?

i’m a female and im around 5,4 my routine is i start with bicep curls which weigh 9kg then i work on my legs e.g leg press then i move onto abs then end with cardio

OMG. We are almost on the same boat.
I'm 164cm and weight 43kg.
I'm working on gaining weight and muscle mass, mostly on my arms. Despite playing basketball my arms are very thin.
As for calories, I try to eat more calories than I burn and eat more protein and "good sugars", mostly fruits...

i’m a female and im around 5,4 my routine is i start with bicep curls which weigh 9kg then i work on my legs e.g leg press then i move onto abs then end with cardio

OK. I would recommend a more comprehensive weights routine, as that will make it easier to gain muscle. What equipment does your gym have, in terms of weights and machines etc.?
Also, what is your diet currently like?

my gym has almost everything except a lat pull down machine (i think that’s what it’s called) my diet so far has been anything really i do eat breakfast, sometimes lunch and dinner but i have snacks inbetween, for breakfast i eat oats with fruits for lunch i eat anything, same with dinner, i haven’t made meal plans yet but i do plan on doing so

Since you have access to a good deal of equipment, for resistance training I'd recommend you follow one specifically designed to add muscle, that targets all of your body's muscles. So maybe something like a four-day upper/lower split, where you do exercises such as squats, lunges, Romanian deadlifts, hamstring curls, etc. on the lower days, and bench pressing (barbell, dumbbell or both), pull-ups (assisted if required), rows, curls, etc. on the upper day. Reps of between 5-15 per set, 2-4 sets per exercise. Try and add weight or reps each time if you can.
Diet wise, don't skip meals. However, oats are definitely good for breakfast. What kind of snacks do you have?