The first thing that you need to do is to figure out if you are going to build your stand for parties that you throw at your home, or if you are looking to sell your hotdogs in a commercial setting.
If you are thinking of going commercial with your cart then you are going to have to buy materials and items that comply with the licensing rules of the local government. You will also have to build your cart to the set standards that they have issued.
This will include the quality of the food and the heating systems that you can use.
Once you have gone on to decide just what it is that you want to do with your cart, you need to go and buy the parts that will make up the cart.
You need to either buy a ready-made cart base, or buy parts that will allow you make a very basic box shape, with wheels and a place to cook the hot dogs in.
You need to get the heating system and the wheels to go on the car as well. Remember to get the propane tank and a generator for your cart as well.
Once you have everything, you need to download the basic diagrams of the cart types that you are allowed to have. Once you have these figures, go ahead and replicate them with the items that you have bought.
Remember to test out everything and put everything under a stress test, in order for it to be safe and secure before you can step out on the street.
You may also personalize the cart via logos and paint jobs which may suit you and your style of selling hot dogs.