Most of the time, there are many projects in your CI server, and you don't wanna a project member execute the other projects jobs.
So to avoid that things happen, use this plugin is a good choice.
Please refer the link below to configure this plugin.
https://wiki.jenkins-ci.org/display/JENKINS/Role+Strategy+Plugin
And below is my configuration for different projects in my company:
(1) Define the Roles
(2) Assign the Roles to users/groups
