How do I us a Form to Collected information from one table and sto

[Rayi]

I need to lookup data in a product table, it has two items, productid and
productname, this is to be used in an order sub form, which needs to lookup
the productid and name and then write it to the ordr detail table, in the
following fields ProductID and ProductName.

I have tried using the following Dlookup. Order_ProductName =
DLookup("ProductName","Products","Productname") The First Items is the Ref
from the Order Table and Form, the Second items is the Product Table, and the
third items is the product table item.
I have also used the following but to no avail.
Private Sub ProductName_BeforeUpdate()
Me.Order_Productname = Me.Productid.column(1)
Me.Order_ProductName = Me.ProdcuName
End Sub.
Can any help me, i have look at example to i am blue in the face but none
show how they work, i have also purchase the Access2003 Book Inside Out.
Starting to setup access