There are a few secrets to house training a puppy, although most of the emphasis will be on you. It is up to you to take control of the training, be consistent, and make sure that everyone in the household takes responsibility as well. It is much easier to train a new puppy than to untrain a puppy that already has a habit of going potty inside.
Here are a few tips about house training a puppy:
A puppy is a baby dog, and when it needs to go potty it will go - so it is imperative to get it outside on a very regular basis - before they have an accident inside. Your puppy needs to go outside regularly just to get them to begin understanding what it is you want of them. It won't take long for them to get the idea, especially if you praise and/or treat when they potty outside.
Very young puppies (8 weeks) have very small, untrained bladders and cannot hold their potty for very long. If they have had no house training at all you will need to start taking them out about every 30 minutes or so. The older a puppy is the longer the time it can be between outside visits, but you still must be very vigilant in your responsibility.
You will need to decide where, exactly, you want them to do their potty. The best way to do this is to take them out to the spot you have designated, and then praise them when they go in that spot. You will be amazed how quickly they will learn if you are consistent with showing and praising. After just a few potties like that they will be going on command - and asking for their treat!
As for the bowels, your puppy needs to go outside as soon as they finish eating. If you feed them several times during the day, take them out to potty several times. They must also go as soon as they wake up in the morning, and the last thing before kenneling them or putting them to bed at night. Give them enough time to go - don't rush - and it won't take long for them to start asking you to go out when they need to.
Never, ever punish a puppy for going potty in the house by rubbing his nose in it or by hitting him! A puppy's nose is 1000x more sensitive than yours, and they will not understand at all. The next time they need to go they will just hide to do their business and will have learned nothing except to be afraid of you.
The best way to prevent an unwanted mess in the house is to watch your puppy, know the signs of an imminent potty time, and take him to his spot to go. Be patient, be consistent, and in no time your puppy will be house trained.