Sub Submit()
        Set objIE = CreateObject("InternetExplorer.Application")
        objIE.Top = 0
        objIE.Left = 0
        objIE.Width = 800
        objIE.Height = 600
        objIE.AddressBar = 0
        objIE.StatusBar = 0
        objIE.Toolbar = 0
        objIE.Visible = True 'We will see the window navigation

        objIE.Navigate ("http://example.com")

        Do
            DoEvents
        Loop Until objIE.ReadyState = 4

        pageSource = objIE.Document.body.Outerhtml
        objIE.Document.GetElementByID("ctl00_ContentPlaceHolder1_txtUserName").Value = "xyz"
        objIE.Document.GetElementByID("ctl00_ContentPlaceHolder1_txtPassword").Value = "123"
        objIE.Document.GetElementByID("ctl00_ContentPlaceHolder1_btnSubmit1").Click
    End Sub

+------+---------------+
| User |    Password   |
+------+---------------+
| ABC  | 123           |
| XYZ  | 456           |
| XCZ  | 777           |
+------+---------------+

Sub Submit(User as string, Password as string)
    Set objIE = CreateObject("InternetExplorer.Application")
    objIE.Top = 0
    objIE.Left = 0
    objIE.Width = 800
    objIE.Height = 600
    objIE.AddressBar = 0
    objIE.StatusBar = 0
    objIE.Toolbar = 0
    objIE.Visible = True 'We will see the window navigation

    objIE.Navigate ("http://example.com")

    Do
        DoEvents
    Loop Until objIE.ReadyState = 4

    pageSource = objIE.Document.body.Outerhtml
    objIE.Document.GetElementByID("ctl00_ContentPlaceHolder1_txtUserName").Value = User
    objIE.Document.GetElementByID("ctl00_ContentPlaceHolder1_txtPassword").Value = Password
    objIE.Document.GetElementByID("ctl00_ContentPlaceHolder1_btnSubmit1").Click
End Sub

Sub Login()
   dim strUser as string
   dim strPassword as string
   dim intLastRow  as integer
   dim intRow  as integer

       intLastRow = Cells(Rows.Count, "A").End(xlUp).Row

       For intRow = 2 to intLastRow
           strUser = Worksheets("MySheet").Cells(intRow, 1).value
           strPassword = Worksheets("MySheet").Cells(intRow, 2).value
           call Submit(strUser, strPassword)
       Next intRow
   End Sub