Training Your Barking Dog to Be Quiet
When your dog barks, say "quiet" and then wag a piece of food in front of his nose. When he stops barking to sniff the treat, P/R (praise and reward).
Do this the next 3 times he happens to bark. On the fourth time he barks, just "pretend" to be holding out a treat as you say "Quiet". When he is quiet, P/R as before. P/R again for every few seconds that he remains quiet after hearing you say "Quiet". Gradually increase the time that goes by between P/Rs.