Puppies tend to have a fairly regular schedule of eating, playing and sleeping, so you should quickly be able to work out when they need to relieve themselves. When they wake up, finish eating or finish playing, take them to the garden or whichever space you have for them to eliminate, and give them plenty of praise when they do. They'll soon learn to associate this with reward, decreasing the number of little accidents inside the house!
If you do come across messes inside, don't scold your puppy for it - they won't associate it with what they've done, and will instead be confused about why they're being told off. This can send mixed messages, and set your training back by several days or weeks; instead, focus on a reward-based training system which reinforces good behaviour.
There are also a number of training aids which will help you teach your puppy the appropriate place to relieve themselves. Take a look at our comprehensive guide on dog house training for more tips and advice on training your puppy.