In SharePoint, each project has its own tasks, assignments, team members etc. While creating projects in SharePoint we have to also create tasks, assignments, team members and custom fields.

Here below is the sample code for creating assignments in projects.    

PublishedProject publishedProject = null; 
DraftProject draftProject = null;
DraftAssignment draftAssignment = null;
AssignmentCreationInformation assignmentInfo = null;
QueueJob queueJobAssignment = null;

try
{
	publishedProject = availableProjects[new Guid(projectId)]; //find publishedProject from all available Projects
	draftProject = publishedProject.CheckOut();

	// Load/read all assignments
	projectContext.Load(draftProject.Assignments);
	projectContext.ExecuteQuery();
	
		assignmentInfo = new Microsoft.ProjectServer.Client.AssignmentCreationInformation();
		try
		{
			assignmentInfo.Id = new Guid();
			assignmentInfo.TaskId = new Guid();
			assignmentInfo.ResourceId = new Guid();
			assignmentInfo.Start = DateTime.ParseExact("2015-01-01 08:00 AM", "yyyy-MM-dd HH:mm tt", null);
			assignmentInfo.Finish = DateTime.ParseExact("2016-01-01 08:00 AM", "yyyy-MM-dd HH:mm tt", null);
			assignmentInfo.Notes = string.Empty;

			// Add the assignment to the checked out project.
			draftAssignment = draftProject.Assignments.Add(assignmentInfo);

			//Update the assignment with the baseline information
			draftAssignment.ActualWorkTimeSpan = TimeSpan.FromMilliseconds(Convert.ToDouble("100"));
			draftAssignment.WorkTimeSpan = TimeSpan.FromMilliseconds(Convert.ToDouble("10"));
			draftAssignment["BaselineWorkTimeSpan"] = TimeSpan.FromMilliseconds(Convert.ToDouble("50"));
			draftAssignment.ActualCost = Convert.ToDouble("500");
			draftAssignment.Cost = Convert.ToDouble("100");
			draftAssignment["BaselineCost"] = Convert.ToDouble(drAssignments[ind]["BaselineCost"]);
			draftAssignment.ActualStart = DateTime.ParseExact("2016-01-01 08:00 AM", "yyyy-MM-dd HH:mm tt", null);
			draftAssignment["BaselineStart"] = DateTime.ParseExact("2016-01-01 08:00 AM", "yyyy-MM-dd HH:mm tt", null);
			draftAssignment.ActualFinish = DateTime.ParseExact("2016-02-02 08:00 AM", "yyyy-MM-dd HH:mm tt", null);
			draftAssignment["BaselineFinish"] = DateTime.ParseExact("2016-02-02 08:00 AM", "yyyy-MM-dd HH:mm tt", null);
		}
		catch (Exception ex)
		{
			// log exception assignment not added
		}
	

	queueJobAssignment = draftProject.Update();
	queueJobAssignment = draftProject.Publish(true);
}
catch (Exception ex)
{
	// log exception assignment not added
}