If Want to add Pepple in Project then you have to select user under the 'Team' tab of Project.

and if you want assign task you can assign task to particular Team meber, and that team member can delegate the task to other.

Khulan

You can assign multiple users to project by defining a Project team.

for that You can use the module https://apps.odoo.com/apps/modules/11.0/project_team/

Thank You

This is almost no question at all. You need to state more information.

Furthermore, do you want to add people to a project OR a task?

[EDIT]

Also: What have you tried for yourself?