how do i use foreign key in wnform

As a example I have a parent table called Customertable and a child table called Ordertable in a one to many relationship. Without using bindingsource how would I link the table up using c#. The database is done in Access 2007

Customertable
FieldName      Data Type
CID                Text
FirstName      Text
LastName       Text

Order table
FieldName    Data Type
OID          Text
CID          Text
Descrip      TextOrder table

If there are examples out there without the use of bindsource please could you forward it to me or if you don't mind can some demonstrate one for me. I know how to create, delete update for single table. Thanks.