Please use below referrence :

How to dynamically add tabs to ASP.Net AJAX TabContainer control

and Use Code

I hope this will help you out

Protected Sub Page_Load(sender As Object, e As EventArgs)
	Dim tbPanel As New TabPanel()
	tbPanel.HeaderText = "TabPanel 2"
	Me.TabContainer1.Controls.Add(tbPanel)
End Sub

I hope this will help you out.