Bicycle Wagon

I want to make a car with bicycle wheels and I now have wheels. How do I go for an axis between the wheels? Is there something I can buy the hardware and if so, will they have different lengths? Should I just saw these things on wheels and, if so, I fear that this happened as I unscrew the draw. If this is not the way, is there welding involved? Ok, this is enough questions, suggestions you can give would be greatly appreciated.

Go to the hardware store and buy the correct size for your axle wheels. At each end of the slip on the shaft washer. Next slide the wheels at each end of the shaft. Now slide on a flat washer. Next drill a small hole on the outside of the washers and install a cotter pin. You should end with a cotter pin, washer, wheel, washer and cotter pin. You wheel does not rotate freely and not the tree. Install the axle with wheels to your car and your ready to go. Good Luck.

get a metal tube that has the id of the same size as the shaft of the wheel, he slips on the axle shaft and soldered