The website is not secur for the certificate problem

Hello.

Which service is hosting your website?
For example, if you have a single Lightsail or EC2, you will need to issue an SSL certificate using Let's Encrypt.
If you use Lightsail's Bitnami WordPress, you can issue an SSL certificate by using the tool as shown in the document below.
https://docs.aws.amazon.com/lightsail/latest/userguide/amazon-lightsail-using-lets-encrypt-certificates-with-wordpress.html
https://repost.aws/knowledge-center/linux-lightsail-ssl-bitnami

If you are using ALB etc., it is possible to issue and link an SSL certificate from an AWS managed service called ACM.
https://docs.aws.amazon.com/acm/latest/userguide/gs-acm-request-public.html
https://repost.aws/ja/knowledge-center/associate-acm-certificate-alb-nlb