You could set them as following, last 2 are not mandatory to get HDFS and YARN working though.
HADOOP_COMMON_HOME=$HOME/opt/hadoop-2.2.0/HADOOP_HDFS_HOME=$HOME/opt/hadoop-2.2.0/share/hadoop/hdfsHADOOP_YARN_HOME=$HOME/opt/hadoop-2.2.0/share/hadoop/yarn