Need to know how to secure my website.

Hello.

An SSL certificate must be issued for the domain for HTTPS access.
ACM can be used to issue SSL certificates in AWS.
However, to use ACM, you must use ALB or CloudFront.
In some cases, it is possible to put an SSL certificate issued by ACM directly into EC2 if the EC2 supports Nitro Enclaves.
https://repost.aws/knowledge-center/associate-acm-certificate-alb-nlb
https://repost.aws/knowledge-center/configure-acm-certificates-ec2
https://docs.aws.amazon.com/acm/latest/userguide/acm-certificate.html
https://docs.aws.amazon.com/enclaves/latest/user/nitro-enclave-refapp.html

If you do not use ALB or CloudFront, you must put the SSL certificate directly into EC2.
Free SSL certificates such as Let's Encrypt can be used.
https://letsencrypt.org/

When managing SSL certificates in AWS, I think it is easier to use ALB or CloudFront and issue them with ACM, considering the management aspects.