The first method is called capturing. Stand in front of your puppy holding some of his dog food or treats. Wait for him to sit – say “yes” and give him a treat. Then step backwards or sideways to encourage him to stand and wait for him to sit. Give another treat as soon as they sit. After a few repetitions, you can begin saying “sit” right as he begins to sit.
Keep your training sessions short, consistent and always have fun. The key to shaping your puppy's behavior is to start out with very easy commands, continue to build on these successes and apply heaps of repetition. Base your puppy training sessions around trust and mutual respect rather than old school methods based on punishment, avoidance and harsh corrections. In this environment you will find that your puppy loves his training sessions and his confidence will grow with each and every session.
It typically takes 4-6 months for a puppy to be fully house trained, but some puppies may take up to a year. Size can be a predictor. For instance, smaller breeds have smaller bladders and higher metabolisms and require more frequent trips outside. Your puppy's previous living conditions are another predictor. You may find that you need to help your puppy break old habits in order to establish more desirable ones.