AmazingPorts bulit in landing portal will be used automatically if you do not set a landing page.
This portal can be customised to your look and feel requirements by changing the appropriate snippets in the "Look & Feel - > List Snippets" section. The snippets are language sensitive and have a fall back structure so that users get the best possible match of language given the language preference setting in the browser.
Usinga "another" landing page/portal
If you set a "URL" in the Network->Network Settings section for landing page, the default portal will display your page below a small frame containing the "voucher" entry and login snippets.