Training puppies can take a little while to get used to, but it's a simple and easily manageable task once you've come to learn your dog's daily schedule. Most puppies will wake up, eat and play at around the same times each day, so it's up to you to establish a routine, learn when they're likely to need to relieve themselves and ensure they're encouraged to do so in the right place.
Keep a careful eye on your puppy, and take them out to the garden after eating or after any extended period of sleeping or playing. Try to implement a phrase like "Be quick!" and give them plenty of encouragement and praise as they relieve. You'll need to keep this up even in the worst weather, as your puppy will need to be told exactly when it's doing the right thing!
It's important not to tell your puppy off if you catch them having an accident indoors, as they may be less inclined to do so in front of you in future, even outside. Clap your hands to interrupt them, and carry them outside to perform your usual "Be quick!" training routine, along with reward and praise.
There are also certain training aids which can help with the process of teaching your puppy:
A pee post is a great tool for training puppies to relieve outside, as you can easily prompt them to do so in your preferred area of the garden. Take them directly to the post when you bring them into the garden, wait until they have finished and give them an immediate reward.
Puppy pads are another useful tool, as they allow you to begin the training process indoors - ideal for puppies which often have accidents! The scent in the pad will attract puppies to it, encouraging them to relieve themselves on it rather than on the floor. Over time, this can then be moved outside to complete your training routine.