I want to start by saying that this is what a tie or lock looks like.  Most people that see it are shocked by how dogs mate as it is not at all what you would expect.  Children think it hurts them because they are "stuck" so here is another good reason why thinking that mating/puppy birth is neat for children to witness....

Tiamo is locked back to back with Tsunami, as he should be in photo 1, in photo 2, you see that Tsunami likes to walk all over the place during this process.  The entire process of mating takes between 15 and 30 minutes and your dogs will want to be alone throughout!  It will begin by the male jumping around the female to entice her, like foreplay.  He will then hump her and become more vigorous.  At this point, the gland in his penis will enlarge and get "stuck" inside the female.  He will then dismount her and try to turn around.  Hopefully he can do this without falling and getting hurt as she is trying to get away.  Hopefully, she will not try to chew off his penis to get it out of her.  When he successfully gets turned, they will remain this way for 15 to 25 minutes before he ejaculates.  They will walk around, like pictured above, this is normal.  When he ejaculates, they will lick their genitals vigorously.  His penis will be long and limp and out of the shaft of fur until blood gets back to it and it will return inside the fur shaft.