[Jenkins][Pipeline][Step1] How to implement Jenkins pipeline with Jenkinsfiles

step1.groovy

#!/usr/bin/groovy
import java.text.SimpleDateFormat
import java.util.*
import java.text.*
import groovy.json.JsonSlurper
import java.util.Date

def GIT_SOURCE_URL ='https://github.com/ohmrefresh/demo-jenkins-pipeline.git'
def API_ENDPOINT = 'https://www.ohmrefresh.club'
def DATE_FORMAT = new SimpleDateFormat("yyyyMMdd")
def SFTP_CONFIG_NAME = "demo-sftp"

properties([
        disableConcurrentBuilds(),
        parameters([
            GIT_SOURCE_URL

                string(
                        name: 'INPUT_DATE',
                        defaultValue: 'today',
                        description: 'YYYYMMDD'),
                        
        ]),
        [
                $class: 'BuildDiscarderProperty', strategy: [$class: 'LogRotator', artifactDaysToKeepStr: '', artifactNumToKeepStr: '', daysToKeepStr: '', numToKeepStr: '5']
        ]
])


pipeline {
    agent any
    environment {
        directory = pwd()
    }
    triggers {
        cron('0 7 * * *')
    }
    stages {
        stage('Validate Parameter') {
            
        }

        stage('Clone Repo') {
          
        }

        stage('Excute SSH Over SSH') {
           
        }
        stage('Call Some API [with httpRequest plugin]') {
           
        }
       

    }

    post {
        always {
            echo 'This will always run'
        }
        aborted {
            echo 'Aborted'
        }
        success {
            echo 'This will run only if successful'
        }
        failure {
            echo 'This will run only if failed'
        }
        unstable {
            echo 'This will run only if the run was marked as unstable'
        }
        changed {
            echo 'This will run only if the state of the Pipeline has changed'
            echo 'For example, if the Pipeline was previously failing but is now successful'
        }
    }
}