You are to select a moral issue you find compelling capital punishment, pacifism, abortion, what have you and say what a deontologist like Kant would say about it.
Then you are to assess that argument. Your paper should, then, be structured like this:
a) Some people grant that capital punishment causes distress and pain to the capital criminal, but say that the criminal has earned his suffering. This is a deontological argument in favor of c.p.
b) Here's what deontology is. La la la.
c) Here's what I think about this deontological justification for capital punishment. La la la.
You should be able to do this in about a single page.