you can't, but if you like the wall so much you can use The Sims 2 Homecrafter plus, which is a bodyshop for walls and floors, you can make it yourself!
Here is the link to download it if you want:
http://thesims2.ea.com/getcoolstuff/homecrafter.php
you can make a house with 2 floors in both sims 1 and sims 2.
You can build 2 floors on Sims 1
yes, just like in the sims 2 you can have multiple floors in a lot
You cant make a house for free you need to pay for every thing even the walls and floors
no.
If you have the sims 2, there should be a little menu on the life of the buy/build catalogue. There will be the hand tool there, and some other small icons. Look for the one that looks like a hammer, and once you select that you can delete walls, floors, etc. Hope i helped.
Most likely not... Sorry but this is true
Ok. If you want more floors go to modthesims2.com and follow these instructions:How_can_you_put_mods_on_the_sims_2
Unfortunately, you cannot use Sims 2 Body Shop on Sims 3.
yes make stairs stairs only exist on the PC version though
No
Any "The Sims" game on the PlayStation 2 platform does not allow you to make any other floors, just the ground floor.