The classes from jars are automatically found by the Jmeter in the following directories:
JMETER_HOME/lib - used for utility jars
JMETER_HOME/lib/ext - used for JMeter components
One point to remember here is that you should jar any JMeter components developed by you and also you need to copy the jar into JMeter's lib/ext directory. JMeter components will be automatically found by the JMeter in any jars found here.
Furthermore you should define