Floors and walls

I am just starting with Torque and playing around with a few things here and there. One question though, how can I make the whole floor and walls solid. Ok, I created a pretty bland house in Torque Constructor with a door (or at least an entrance..there isn't really an actual door), and 3 windows (one on the front, two on the back).

I exported it into the game. It was pretty annoying to get it situated correctly so that the player can enter it and there is no ground coming through the bottom, but I got it decent enough for now; however, when I test it, the player does not stay on top of all of the floor and sinks into it here and there. And it is also possible to run through the back wall

Any help, guys? And can someone point me to some good tutorials? I'm playing around with the Torque for Teens book, but it is not as helpful as I would like. Thanks!