First of all If you do not have Jmeter installed, download Jmeter from http://jmeter.apache.org/download_jmeter.cgi
To have the plugin functional in you Jmeter you have to Download latest JMeter plugins from http://jmeter-plugins.org/?utm_source=jpgc&utm_medium=link&utm_campaign=main
And then follow the below steps,
1. The user is able to set the number of users in the This group will start threads field.
2. If you set up for First, wait for field a value the test will stay and wait how much time have set up and then will start (below is set to 1 so 1 sec will wait before the test will start)
3. In the Then start . threads every....seconds field the user will set the number of threads. (the field is very good if you have a scenario where all the users should not start in the same time)
4. The field Then hold load for ...second is the one for the duration of the test. Basically, how it's working...after all the users are up the test will run with all users for the period set in the field.
5. The last fields Finally, stop...threads every seconds will stop the threads after the period set is over.