Try browsing to the ResourceManager:
http://$resourcemanager.full.hostname:8088/
Smoke test using Terasort and sort 10GB of data.
su $HDFS_USER /usr/lib/hadoop/bin/hadoop jar /usr/lib/hadoop-mapreduce/hadoop-mapreduce-examples-2*.jar teragen 100 /test/10gsort/input /usr/lib/hadoop/bin/hadoop jar /usr/lib/hadoop-mapreduce/hadoop-mapreduce-examples-2*.jar terasort /test/10gsort/input /test/10gsort/output