How are motors connected to wheels?

Hi, I am trying to figure this quick problem out. I am picking up on a project that a previous student left behind.
She made a list of hardware to be ordered and included in this list was a a motor, square shafts, shaft collars, delrin bearings, and wheels.
How do these things come together?

motors : http://www.robotshop.com/ca/en/vex-2-wire-393-dc-gear-motor-motor-controller-29.html
square shafts: http://www.robotshop.com/ca/en/vex-12in-square-bars-2pk.html
wheels : http://www.robotshop.com/ca/en/vex-wheel-kit.html
delrin bearings: http://www.robotshop.com/ca/en/vex-delrin-bearings-10pk.html

edit: this is the chassis im thinking of using http://www.vexrobotics.com/media/catalog/product/cache/91/image/5e06319eda06f020e43594a9c230972d/c/h/chassis25x25x2-wheels.jpg

It looks like the wheels shown on that chassis don't have any bearings.

Looking at the VEX site (http://www.vexrobotics.com/276-1209.html) it looks like the "Bearing Flat" gets bolted to the chassis through two of the holes and a square shaft goes through the third hole.

The wheels either press onto the square shaft or slide onto the square shaft and are kept in place with shaft collars.

The motors connect to the shaft directly or with gears or a chain drive.

How do these things come together?

Well, perhaps you need to describe the desired end product robot. You may be able to complete the project easier/cheaper by using parts and concepts different from the previous student. How much weight is the robot supposed to carry?