How do you use a dichotomous key to discover the scientific name of an organism

You start by answering the first question on the list which tells you what to do from there. Pretend your animal was a bird, you might have a key like this:

Does this animal have wings?

yes go to question 2

no go to question 6

Then you just continue until the list doesn't say to do anything else. i. e.:

Is the animal feathered?

yes bird

no go to question 4