Search Button For Simple WebBrowser

For the simple web browser I am creating I would like to have a combobox displaying different search engines and a button that would take the user to the selected search engine's website address.

Here is the code to load the search engine options:
vb.net
Private Sub Form1_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load
ComboBox2.Items.AddRange({"Google", "DuckDuckGo", "Mahalo", "Ask"})
ComboBox2.SelectedIndex = 0
End Sub

And here is the search buttons
[Code] .....