Most browsers have a pop-up blocker menu that appears when a pop-up is blocked. The browser can usually be set at that menu. If not -
To set your browser to allow pop-ups from this site:
In Internet Explorer, click "Tools", then "Internet options", then click the "Privacy" tab.
You should see this window:

You can either just turn off your pop-up blocker (not recommended) or -
Click the "Settings" tab. You should see this window:

The website name should be in the allow window. If the website name isn't there, copy and paste it into the allow window and click the "Add" button. Click "Close" and your browser should be set. Other browers like Firefox and Netscape will be similar.