Need to know how to get the users of multiple role from a Library context and add them as a project manager in the project context

Im using windchill 10.1 M030, We have written a code for creating project automatically based on the lifecycle state of the document. When the document is released, the project will be created by the listener. Now the users are added manually in the respective roles in the project. Instead i wanted to add a particular members of a role from library as a project manager in the project context. Need help with this.