If you've tried building your own HTML tiles, you may seen links open inside the tile instead of its parent window, or a new tab. Because Jive tiles are displayed as iFrames, links with unspecified targets will open within the tile itself. The solution is to add the target attribute to your link.
Setting the target to "_top" will replace the current browser page with that link. Setting it to "_blank" will force the link to open in a new window or tab.
Here's where to place that attribute in your code: