There may be other ways but one way to do this is to use CreateObject with
InternetExplorer.Application.  Then you can navigate to a web page using the
IE object model. Since you are calling CreateObject, your form template will
need to be in full trust mode.

Here is rough pseudocode:

Dim IE As ShDocVw.InternetExplorer
Set IE = CreateObject("InternetExplorer.Application")

IE.Visible = True
IE.Navigate(http://foo.com)

There is more information about the InternetExplorer object in MSDN.

There are various other ways to do this but this is the first one that comes
to mind.  One other way would be to use the Shell object's ShellExecute
function. However, each of these solutions involves an ActiveX control which
means that your solution will need to be full trust.

- Scott