Timer code help please!

[El Don]

I'm trying to program a countdown timer that shows the time in a label, with a button to start it, and if the button is pressed again add certain amount of time, for example 1 minute. Can anyone help me please? I need it for my biology class.

[White95dp]

Dim iClock As Integer

Private Sub Command1_Click()
If Timer1.Enabled Then
iClock = iClock + 60
Else
Timer1.Enabled = True
Label1.Caption = "0:00"
End If

End Sub

Private Sub Form_Load()
iClock = 0
Timer1.Interval = 1000
Timer1.Enabled = False
End Sub

Private Sub Timer1_Timer()
Dim iMin As Integer
Dim iSec As Integer
iClock = iClock + 1
iMin = Int(iClock / 60)
iSec = iClock - iMin * 60
Label1.Caption = iMin & ":" & Format(iSec, "00")
End Sub