Your vivarium will need to be secure as Corn Snakes are escape artists!
I prefer the vivariums with the sliding doors. With these they open at the front and either a lock or a wedge can be placed on the doors to prevent the snake from pushing them open.
You must always ensure that there is sufficient ventilation it the vivarium, most vivariums will have vents in them already.
A snake friendly substrate needs to be placed on the bottom of the vivarium. I use Beech Chips but you can also use newspaper although this looks less attractive. There are other products available but do make sure they are Corn Snake Safe. Any type of sand is a big No No!! This will dehydrate the corn and prevent a good shed and can also lead to breathing problems and infections. If possible put about 1 inch of substrate in the vivarium as Corns sometimes like to burrow underneath.
A heat mat will need to be placed at one end of the vivarium covering about 1/3 of the viv. This is essential as snakes need to have a cold part and warm part of the vivarium to regulate their boby temperature.The tepmerature of the warm end should be between 82-86 F and the cool end should stay around the 65-75 F mark.
There is no requirement for lighting but I personally use it just for effect. It is best to use a light that doesnt give off much heat, mine is a 1.5foot strip light which is covered with a plastic guard so the snake cannot be burnt. All lights must be covered with either plastic or mesh guards at all times. It is also best to turn them off at night.
A water bowl must be present at all times and water changed on a daily basis. The bowl should be big enough for youre snake to fit inside as they sometimes like to bathe. You will be lucky to catch them doing this though! I have yet to see it.
You will need to hides, one in each end of your vivarium and these should be big enough for your snake to fully fit in.
You can also add plastic plants (these are best as youre snake will probably dig up real ones and they can cause bateria and bugs), branches for climbing (again plastic are best but if you decide to use real ones the fruit trees are the best and fully clean with salt water and leave to dry).