Amabri: Unable to see the link to add properties in Ambari

I running Ambari Verion 2.1.0

I need to modify the following files prior to installing HUE but I don’t see a link to add a property in either of the custom hdfs-site, custom core-site sections and
I don’t even see a custom option for Oozie and Hive:

1. hdfs-site.xml file, on the NameNode, Secondary NameNode, and all the DataNodes, add the following property:

<property>
<name>dfs.webhdfs.enabled</name>
<value>true</value>
</property>

2. core-site.xml file. on the NameNode, Secondary NameNode, and all the DataNodes, add the following properties:

<property>
<name>hadoop.proxyuser.hue.hosts</name>
<value>*</value>
</property>

<property>
<name>hadoop.proxyuser.hue.groups</name>
<value>*</value>
</property>

<property>
<name>hadoop.proxyuser.hcat.groups</name>
<value>*</value>
</property>

<property>
<name>hadoop.proxyuser.hcat.hosts</name>
<value>*</value>
</property>

3. oozie-site.xml file, on the Oozie Server host, add the following properties:

<property>
<name>oozie.service.ProxyUserService.proxyuser.hue.hosts</name>
<value>*</value>
</property>

<property>
<name>oozie.service.ProxyUserService.proxyuser.hue.groups</name>
<value>*</value>
</property>

4. hive-site.xml file, on the HiveServer2 host, add the following properties:

<property>
<name>hive.server2.enable.impersonation</name>
<value>true</value>
</property>

Where do I need to look for find the link to add these properties in Ambari please?

Thank you in advance.