It is straight forward, however you might have trouble buying just one spoke. Plus you must get the same length spoke. Do you have the correct replacement spoke?
I don't have the new spoke yet. I do have the boken spokes (get this there are 11 of them broken). I just bought the bike for my son and knew they were broken. The other kid lost the chain and wiped out a few of them but kept riding and broke the rest is what I think.