Access to SECollab users and projects management is done from the server administration page. An administrator can create and edit projects under the Projects tab, as well as create and edit users under the Users tab.
Under each project administration's "Project members" tab, a project leader can add users to the project and assign them one or several roles.
Users can be organized into groups. In order to do that, you first need to create the groups in the corresponding administration pane. Then in the members pane, you can assign one or more groups to project's members.
In order to create proper traceability on a project, you may want to set up associations with other projects in friend applications. For that, you will need your server administrator to properly setup the communication between your SECollab server and your friend application server, may it be Atlassian JIRA with the OSLC Connect for Jira, PTC Windchill with the OSLC Connect for Windchill, IBM's CCM application in the CLM suite, or other compatible OSLC-enabled application.