How can I make this little 'den'?

[lullabies]

Hi guys!

http://www.youtube.com/watch?v=UaLIL9wBhj0
This house looks lovely, but one thing caught my eye. The little 'den' sorta thing. It's basically a few steps of stairs going down to this area of land that's a little underground.
0:24-26, 0:57

How do I do this? O__O I don't exactly know what this type of area is called so googling this was challenging, so I came to my last resort, which was to ask here ._.

Thanks!

[romagi]

The house is built on a foundation. They have cut out part of the foundation and put steps down to the ground level. :)

[fluttereyes]

Looks like it's already built. Why don't you email the poster of the video and as where you can download it?

[Darim]

You should look at the split-level building tutorials. It includes warping walls to different heights using the 'constrainfloorelevation' cheat. It's abit advanced, I know many don't like using the cheat, but there are lots of cool things you can do with the tecnique, and something I use on almost every house I make. Here's one tutorial: http://www.modthesims.info/showthread.php?t=350293

[HugeLunatic]

The sunken living area doesn't need any CFE cheats to build. It is like romagi mentioned. Build the house on a foundation then remove a section of the foundation. The tutorial by beefysim linked above uses CFE because the sunken living area is next to an outside wall. If you don't put the sunken living area next to an outside wall then no CFE cheat is required.

[snrubsy]

It does really depend if you are building on a n outside wall. If you are just building it the middle of the house you just need to delete a section of the foundation, put a floor down and lay some stairs, but if it has a wall on the outside of the house you will need to look at split levelling. It is best to look at youtube videos for this because that's the best way to see how to do it. :)