How to configure private docker image using Amazon Elastic Container Service Jenkins plugin

I am using plugin: Amazon Elastic Container Service (ECS) to create Jenkins agents. I want to configure in ECS agent templates section(from the “configureClouds/ “Jenkins page) to pull private docker image. Which is based of jenkins/jnlp-agent How do I configure it under “Docker Image” . (For public docker images I just give “jenkins/jnlp-agent” under “Docker Image”) Any pointers will be really helpful

pipeline {
    agent {
        label 'label1'
    }
    
    
    stages {
        stage('build') {
            steps {
              sh 'pwd'
            }
        }
    }
}