In continuation from here

Before you mail a file from Outlook, click on the menu Project | Add Reference. You will be presented with a Add Reference dialog box. Navigate to the COM Tab and select the Microsoft Outlook Object Library. Once done simply use this code. Amend as applicable.

Imports Outlook = Microsoft.Office.Interop.Outlook

Public Class Form1
    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click
        '~~> Define your Outlook Objects
        Dim objOutlook As New Outlook.Application
        Dim objEmail As Outlook._MailItem

        Dim body As String
        Dim ExcelFile As String = "C:\Sample.xlsx"

        objEmail = objOutlook.CreateItem(Outlook.OlItemType.olMailItem)

        body = "Hello World," & vbCrLf & vbCrLf
        body += "This is my First email from vb.net. Please find attached the Excel file" & vbCrLf & vbCrLf
        body += "Regards," & vbCrLf & "<Your Name Goes Here>"

        With objEmail
            .Subject = "My First Email"
            .To = "EveryOneInThisWorld@Universe.Com"
            .Body = body
            .Attachments.Add(ExcelFile)

            '~~> Show on screen
            .Display(True)

            '~~> Uncomment the below to actually mail the file
            '.Send()
        End With
    End Sub
End Class

This is how you email will look like if you ran the above code