First, get your dogs favourite toy or just yourself is fine.
Ask your dog to sit and wait. If your dog doesn't know how to sit and wait, then you may need a helper to hold your dogs collar for you whilst you get setup.
Go to another room in the home or somewhere in your backyard where you dog cannot see you.
When you're in your hiding spot, call your dog to come and fins you. Only call out once unless you feel like they didn't hear you properly.
Your dog will then start looking for you, by following your scent and also the sound they heard.
As soon as your dog finds you, toss their favourite toy to them and play a game or get excited when they see you.
Teaching your dog to discover things using only their nose is a great game for the body and the mind.
While all dogs have a great sense of smell, sometimes they have to be reminded to use it, and this exercise can get your dog excited about solving the problem of the hidden treat or suprise. Set up a bunch of boxes or dark containers (start with at least three or four) upside-down next to each other and, without your dog seeing you hide it, place something they like (a favourite toy, a bone, a treat, whatever works) under one of the containers.
Next, encourage your dog to smell the boxes and as he/she pauses or shows attention at the one with the suprise, lift up the box and enthusiastically congratulate him on his discovery. Let him eat the treat, fetch the toy, or indulge in whatever surprise your dog found.
Soon, your dog will know what's expected during this game and be excited to sniff out the prize. Keep adding more boxes and space them at farther intervals to increase the challenge as your dog's scent work improves.