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.
Always remember that you are dealing with a very immature young animal. Be realistic, flexible, patient and always fair during puppy training sessions. Your puppy doesn't just automatically know this stuff! It's all new to him and he is bound to have the odd slip up and mistake along the way. Don't worry about these mistakes, just move on and do your best to prevent them in the future.
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.