Creating A Sp Procedure And A Trigger Help

There are 2 tables: OrderID and Order_Details
CREATE TABLE Orders
(OrderID int
Constraint Order_ID_pk primary key
, CustomerID nchar (5)
, EmployeeID int
, OrderDate datetime
, RequiredDate datetime
, ShippedDate datetime
, ShipVia int
, Freight money
, ShipName nvarchar (40)
, ShipAddress nvarchar (60)
, ShipCity nvarchar (15)
, ShipRegion nvarchar (15)
, ShipPostalCode nvarchar (10)
, ShipCountry nvarchar (15)
)

CREATE TABLE Order_Details
(OrderID int NOT NULL
, ProductID int NOT NULL
, UnitPrice money NOT NULL
, Quantity smallint NOT NULL
, Discount real NOT NULL
, constraint Order_Details_PK
Primary key (OrderID, ProductID)
)

Create a Transact SQL procedure, customer_activity, that would, for a given CustomerID, return the number of orders that customer has made, average amount of all the customer orders, and the maximum customer’s order. The CustomerID should be the stored procedure’s input parameter. The stored procedure should use the view customer_orders.

what kind of code to create this? it says i need to use a view customer_orders, which i made:
create view customer_orders as
select orders.orderID, customerID, sum(order_details.orderID) as orderamount
from orders, order_details where orders.orderID=order_details.orderID
group by orders.orderID, customerID

but i don't know how to do it.


Next: the trigger:
Write a trigger that would, for any order entered (inserted), print the order amount as well as the customer’s average and maximum order so far, by using the view and the stored procedures created in this lab.

please and thank you