Weaning puppies is a perfectly natural process. Mamma dogs have been doing it successfully for ages, so how hard can it be, right?
But humans, not being dogs, can sometimes forget the natural part, and get confused about it.

Fact is, weaning puppies is an easy, logical process.

When you're ready to begin weaning your new puppies, keep in mind that this should be done gradually, in small steps. You can’t rush it, and you definitely don't want to begin when the puppies are too young.
Sometimes people get impatient and try to begin weaning puppies before they're three weeks old. That's too early. Their bodies need to develop the ability to handle solid food, and that takes time. Wait the three weeks -- it's not really so long.

The first step in the weaning process is to take the mother away from the puppies at least an hour before it’s time for them to eat. This gives the puppies a chance to get good and hungry.
They'll be more inclined to try the new, alternative food you offer them.

Remember, when it’s time for the puppies to eat, the mother should be nowhere around.
The alternative food you offer them should be liquid or semi-liquid so it's easy for them to swallow and digest. Solid food won't work for them yet.
You can make a gruel of commercial dog food mixed with water or baby cereal thinned with water. Another option when weaning puppies is to use diluted strained baby food.
Put any of these mixtures in a small, shallow dish. Some of the puppies will have no problem eating. They'll catch on immediately. But there may be a few that just don't get it. So they'll need some encouragement. The easiest way is to put a little of the mixture on the tip of their nose or on their tongue.

When weaning puppies you'll also need to decrease the amount of food you're giving the mother. This causes her to produce less milk. At the same time, you can gradually begin increasing the amount of food you give the puppies, and over the next several days make it less soupy. As they grow and their digestion matures, their food should slowly become more solid, day by day.

Weaning puppies at this point becomes easier because, as the solid food grows more familiar to them, they learn to enjoy it more. Let them eat as much as they want as long as they don't become bloated.

If you approach weaning puppies like this, the process should be simple, painless and easy. Expect to see them completely weaned by the time they're six to eight weeks old.