How do I teach My puppy to ask to go outside? He knows he is supposed to go out,but does not ask.

He doesn't understand yet how to ask. You've got to teach him. Here's some advice from Aurora_Bell, one of our dog experts --

The one fool proof key to house breaking is consistency. As soon as puppy eats or drinks he goes out side. Say the same potty words all the time, like "Go potty" or "Potty time." And it helps if you wait out there with him until he does his business, and when he does it's time to praise, praise, praise! Even offer a small treat at first.

Don't use puppy pads or paper train, that only confuses puppy. He will have accidents, but unless you catch him red pawed in the act, there is no sense in "bad dogging" him.

NEVER rub his face in any mess he makes, or he will become afraid of you.

Another dog expert said this --

Make sure puppy gets plenty of opportunities to go potty. At this age he will have to go more often than an adult dog. Tons of praise, never be negative. It's normal for a puppy to have accidents. He has to learn what you expect of him, what is acceptable. Repetition, praise, treats, lots and lots of positive reinforcement. This may take a while, especially because he's still fairly young and cannot hold it like an older puppy can. Usually they gain more bladder control at around 4 months of age.

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How old is he? How long have you had him?

You train him by taking him out without him asking, at regular times, about 4 times a day. Dogs have very good internal clocks and like routine.
He will let you know when he has to go out at any other time soon enough, by walking towards the door and back to you, or pacing, or licking himself.
He will quickly learn 'Do you have to go out?' from the tone and inflection of your voice, and you can say that each time you take him out anyway.
Then he will dance around in an 'affirmative' way.
Many dogs don't bark to be let out, even if they bark to be let in.