You have to eat more to grow, yes. That is typically called a 'bulk'. The body can only synthesize so much muscle in any given time, estimated at around 1/2 kg per week. So typically we advocate for around an excess of 300-500 extra calories per day, to maximise muscle gains while minimising fat gains. But do expect with any calorie excess to gain some fat despite your best efforts.
Heavier weights/ less reps is such a broad term and honestly, that in itself means nothing. What constitutes heavy? What is "less" reps? Less than what?
The best way, especially for a new lifter or someone without knowledge is to follow a reputable hypertrophy program rather than try develop your own. Doing this will only result in muscular imbalances considering you are more than likely to miss certain phasic muscle groups which will lead to imbalnces over time (postural issues, weakness issues etc.) or over emphasis smaller accessory movements and under emphasize larger muscle groups.
I'll give you my example; remember though that this works for me but my not work for you; I wont list exercises though.
Firstly, I tend to do a lower/ upper split twice per week. The reason for this is that there is evidence to suggest that increased frequency will lead to more 'gains' but to do this you must decrease total workout volume each day to allow for the decrease in time between each workout. I typcially aim for 6 reps to begin with (1-2 shy of failure) then the next session the following week I aim for 7 or 8 or whatever I can get still maintaining that 1-2 shy of failure then the next week I aim for 10. Then I have a deload week and reset. Once I can get 10 reps of my starting weight I then move up 2.5kg or 5kg or whatever it may be until I can only do 6 reps again (1-2 shy of failure) then repeat the phases described before (moving up in reps, not weight per week) deload and repeat.
This is just one example though.