Since you said only one node, I am not sure if you mean there is only one physical machine in the cluster. if that is the case, you want to enable something called pseudo-distributed mode, where all processes, that is namenode, datanode etc. are going to run on the same machine.
You can find instructions here.
https://hortonworks.com/hadoop-tutorial/introducing-apache-ambari-deploying-managing-apache-hadoop/
On the other hand, if you want to run namenode on a single machine -- but you have a set of physical nodes, you can use Ambari normally. if you want to use Amabri, You can select HDFS and the standard installation does not assume that you have HA. If you want to turn on HA then use HA Wizard.