I am hoping someone can explain a bit of sql to me as I am having a difficult time getting my head around some of the concepts and reading seems to be more confusing

I am hoping a real world example might help me. I have a sql database with an existing table that is populated from another table and inserted using sqlBulkCopy

I would like now like to be able to add records to the Table perferably multiple records that come from a DataTable that is created from a csv file using the TextFieldParser class. I was hoping to add these at one time or with one statement, sub or function etc...

I am trying to follow the this code I found in the codebank and I honestly don't understand it so I cant determine what to do, this is what I have so far

Code:
Dim str As String = ("F:\email\emailtest.txt")
        ReadTable2(str)
        Dim col0 As String = Table2.Columns(0).ColumnName
        Dim col1 As String = Table2.Columns(1).ColumnName
        Dim col2 As String = Table2.Columns(2).ColumnName
        Dim col3 As String = Table2.Columns(3).ColumnName

        Using connection As New SqlConnection("Data Source=.\SQLEXPRESS;AttachDbFilename=C:\Users\Bill\Documents\Visual Studio 2008\WebSites\Emailer\App_Data\Database.mdf;Integrated Security=True;User Instance=True")
            Dim insert As New SqlCommand("INSERT INTO Contacts (LicenseNumber, FirstName, LastName, Email) VALUES (@LicenseNumber, @FirstName, @LastName, @Email)", connection)
            Dim Adapter As New SqlDataAdapter("SELECT * FROM Contacts", connection)
            insert.Parameters.AddWithValue("@LicenseNumber", col0)
            insert.Parameters.AddWithValue("@FirstName", col1)
            insert.Parameters.AddWithValue("@LastName", col2)
            insert.Parameters.AddWithValue("@Email", col3)
            insert.Parameters.AddWithValue("OptOut", 0)
            Adapter.InsertCommand = insert
            Adapter.MissingSchemaAction = MissingSchemaAction.AddWithKey

            Dim updatetable As New DataTable

            'Retrieve the data.
            Adapter.FillSchema(updatetable, SchemaType.Source)

            'Add the new rows to the DataTable, e.g.
            Dim row As DataRow = updatetable.NewRow()
           
            row("LicenseNumber") = (row(1)(col0))
            row("FirstName") = (row(col1))
            row("LastName") = (row(col2))
            row("Email") = (row(col3))
            row("OptOut") = 0

            Table.Rows.Add(row)

            'Save the changes.
            Adapter.Update(updatetable)


        End Using
Again I do NOT know what I am doing I seem to be competely lost with sql and particuarly parameters. So of course this code is no where near accurate for what I am trying to achieve, I am hoping someone would be kind enough to give me a break down of what it is supposed to be doing or what I am supposed to be doing in order to achieve my end result of