On the bottom of the interface there is a section with 2 vertical tabs: Timeline and Browser.

When you go to the Browser, the last horisontal tab inside it is Content (by the way, make sure you check out all the other tabs and load stuff in and look at how the scenes/shaders/lights are set up -- great educational experience). In the content you should have some runtime that has installed with your Carrara content.  In the top right corner od this little Browser section there is a "file menu" icon, looks like a piece of paper with folded corner. When you are in the Content tab, click on this icon and go down to "Add Runtime" then open your Poser Runtime and it will become accessible through Carrara. You can add multiple Runtimes this way.

Welcome to Carrara! :) It's fun! And Happy New Year!