im assuming you are geolocating?
you could do something like this:
<asp:textbox id="TextBox1" text="40.78" runat="server" xmlns:asp="#unknown"></asp:textbox>
<asp:textbox id="TextBox2" text="-81.5" runat="server" xmlns:asp="#unknown"></asp:textbox>
<asp:image id="img1" runat="server" imageurl="" xmlns:asp="#unknown" />
<asp:button id="Button1" runat="server" text="go" xmlns:asp="#unknown" />
on button click
code behind:
Protected Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
img1.ImageUrl = "http://www.latlong.net/c/?lat=" + textbox1.text + "long=" textbox2.text + "alt=latlong"
End Sub