A lawyer isn't needed at this point. The appeal process is very easy. Im sure they have you the directions but all you need to do is fax or mail the application form with the refusal letter, to the designated IAD office of your province. Im pretty sure that's it, but just double check the instructions that they gave you
from there your case worker will handle everything else. When they contact you, just explain why you were denied and explain that you have the required documents (divorce papers) being processed at the moment.