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

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

PublishedProject publishedProject = null;
DraftProject draftProject = null;
TaskCreationInformation taskInfo = null;
DraftTask draftTask;
QueueJob queueJobTask = null;

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

	// Load/read all draft tasks
	projectContext.Load(draftProject.Tasks);
	projectContext.ExecuteQuery();	
	
		try
		{	
			taskInfo = new TaskCreationInformation();
			taskInfo.Id = new Guid();
			taskInfo.Name = "Scope";
			taskInfo.Duration = "200.000000";
			taskInfo.ParentId = "Task Parent Id";
			taskInfo.IsManual = true;
			taskInfo.Start = DateTime.ParseExact("2015-01-01 08:00 AM", "yyyy-MM-dd HH:mm tt", null);
			taskInfo.Finish = DateTime.ParseExact("2016-01-01 08:00 AM", "yyyy-MM-dd HH:mm tt", null);

			// Add the task to the checked out project.
			draftTask = draftProject.Tasks.Add(taskInfo);

			//Add the rest of the fields
			draftTask.IsMarked = false;
			draftTask.ActualCost = Convert.ToDouble("0");

			//Now update the task with the rest of the custom fields
			draftTask[internalname] = "Custom field Internal Name";		
			
		}
		catch (Exception ex)
		{
			// log exception task not added
		}
	
	// Update the draft project collection.
	queueJobTask = draftProject.Update();
	queueJobTask = draftProject.Publish(true);
}
catch (Exception ex)
{
	// log exception task not added
}