How to pass text to web page search box ?

How to Set obj = ie.Document.all.Item("???")

Option Explicit
Sub Testing_1()
Dim ie As InternetExplorer
Dim obj As Object
'~~ Prepare to open the web page
Set ie = New InternetExplorer
With ie
.Visible = True
.Navigate "http://www.yahoo.com/"
End With

'~~ loop until the page is fully loaded
With ie
Do Until Not .Busy
DoEvents
Loop
End With
Set obj = ie.Document.all.Item("searchlabel")
If Not obj Is Nothing Then
obj.Value = "Testing"
End If

Set ie = Nothing
MsgBox "Done"
End Sub