To install Hadoop using Ambari setup, you first need to have the Ambari server installed on a master node or server. Once Ambari server is set up, you can access the Ambari web interface using a browser. From there, you can create a cluster and add nodes to it. During the cluster creation process, you will have the option to select the Hadoop components you want to install, such as HDFS, MapReduce, YARN, etc.