1st: have it checked by a competent electrician who can calculate current draw for the elements and check that the elements are not broken.
2nd: have same electrician tell you if your existing wiring can safely deliver the required current.
3rd: have same electrician tell you if the top and bottom half are indeed electrically separate. If so they are either on or off. temperature control will be difficult though it would be possible to make a switch box that will run both elements in series. that would result in half power setting.
That is how most older kilns acheived a low/high power setting.

If it checks out ok with your electrician and you want to fire it as is, you'll have to use the plugs as switches. Run the bottom element for 15 min then of for 5. Do this until the temp gets close to 200f and try to hold that for an hour or 2. After that plug in top and bottom and keep an eye on it.

Wow, I know this is an old post, but I would like to add my 2 cents! For a kiln, I always consult a ceramic shop. They either know or can refer you to someone who does know about kiln problems.

I am not sure all electricians would know specifically about kilns. But maybe the ceramic shop can refer you to one who does.

Are their coils in it? Is there any type of name on it? Anywhere? I would love to see an update about this! Thanks! Rosie

Go to the thread titled "Received Kilm" This person told how they got information about kilns. (yes she spelled kiln wrong, but the information she received may help you. Rosie