Help in WCF, update List(Of entity) into database

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C#

VB

WCF

Dear all,
I'm doing a WCF project. I have a interface:

Public Interface IProxy
    <OperationContract()>
    Function fnGetAnChi(MauSo_ As String) As List(Of TenAnChi)
    <OperationContract()>
    Function fnSaveAnChi(lstAnChi As List(Of TenAnChi))
End Interface
<DataContract()>
Public Class TenAnChi
    <DataMember()>
    Private MauSo_ As String
    Public Property MauSo() As String
        Get
            Return MauSo_
        End Get
        Set(ByVal value As String)
            MauSo_ = value
        End Set
    End Property

    <DataMember()>
    Private AnChi_ As String
    Public Property AnChi() As String
        Get
            Return AnChi_
        End Get
        Set(ByVal value As String)
            AnChi_ = value
        End Set
    End Property
End Class

I was loading data from table successfuly then i removed, added items into list over the operations in List. The function fnSaveAnChi need to update data stored in list into a table in database with column name same with properties in class TenAnChi. I want to re-define Function fnSaveAnChi(lstAnChi As List(Of TenAnChi)) in implemented class to do. I wish i do that over LINQ. Pls help me!