By default these Hadoop configuration files are found in hadoop/conf directory.
For configuring HDFS you have to edit core-site.xml and hdfs-site.xml files.
core-site.xml:
<property>
<name>fs.default.name</name>
<value>hdfs://localhost:8020</value>
</property>
In hdfs-site.xml:
<property>
<name>hadoop.tmp.dir</name>
<value>/directory/</value>
</property>