Typically the directory the file would be stored in is defined by you.
Assuming you use the copyFromLocal command,
hadoop fs -copyFromLocal /Users/Example.txt /user/ The file, Example.txt is stored in /user on hdfs.
You can also use the command,
hadoop fs -ls to view the files in that particular directory. Similar to the ls command in linux.
If you have Ambari, you can also view the uploaded files via ambari.
Log in to ambari > services > hdfs > quick links > namenode ui > browse the file system.