To assign access to task lists:
Open the Manage Task Lists page.
See Managing Task Lists.
In the Task List area, select Actions, and then select Assign Access.
Select the users or groups to access the task list.
Click Users to display all user names; click Groups to display all groups.
If there are multiple pages of users and groups, type the page number to go to in Page, and click Go.
Click Start or End to navigate to the first or last page.
Click Prev or Next to move to the previous or next page.
For Type of Access, select how users or groups can use the task list:
Assigned: View and use
Manage: Modify
Manage and Assign: View, use, and modify
None: No access