hloo mam for that you need to make him stand with you while you are brushing and slowly he will see you doing that he will also get a habit of that but forcing him won't help you show him different video so that he gets to know that it's important You can also practo consult us regards

My child was fussy too.. jus start brushing with them. Show them videos of kids brushing their teeth. If nothing works u need to force them to let them know it's mandatory to brush! Third day he/she will start brushing automatically. But u need to stay with them all the time, n make it more interesting and a fun activity!

Brush your teeth in front of him,encourage him.. bring intrusting tooth brushes,and .. introduce lots of fibrous things in his diet,.. fibrous food help to keep our teeth surfaces clean. Keep trying, don't give up,have  patience,as prevention is always better than cure.

you can use a power tooth brush so that he brushes and plays at same time

You just need to keep talking to him and make it a fun activity. Show him fun videos on brushing and also take him to a dentist. A dentist telling him to brush will be more effective than you telling him to do so