Scent Games: ELI5

Hello, I am looking for some indoor-enrichment activities for my 10 mo Bichon pup and stumbled across scent games. Unfortunately, I don't really get it and I feel like I'm missing some obvious information.

Judging from reddit posts and google searches, scent games basically involve hiding some scent around your home and having your dog go sniff for it. However, I don't get how people signal their dogs that there are scents to be found and that the game begins, so to speak? Are they expected to just pick up on it on their own? Could it be that my dog is just not very good at tracking stuff with her nose? She often takes a good 30-40s for her to sniff around on the otherwise empty floor and find a treat that has been tossed right next to her..

What I also don't really get is what kind of scents people use. It seems that there are kits being sold that basically contain essential oils? Why are dogs interested in those? It seems to me the only scents my dog is interested in are those of treats and human food. How does a dog know which scents are part of the game and which aren't?

Are scent games supposed to be a supervised activity, i.e. I follow my dog around until she finds the random scented object and reward her with praise and treats, or is the object itself the reward (because it's a treat or a toy?) And do you typically only hide one scented object or several? Is a dog able to tell when the game is over because all scents have been found?

We did try and hide a treat inside a towel or a cardboard box and she picked up on that, although I wouldn't really say that the appeal in the game was in the sniffing rather than in the shredding of things to get to the treat.

Also, what do you do with the scented object once it has been found? It's not like the scent just goes away – how does the dog understand that the scented object being tucked away in a box or a shelf is not just part of the game?

That also brings me to the question of good hiding places. Where do you hide the scents? Are closed cupboard doors off-limits? What about hiding something under a bowl or a box? What does hidden exactly mean to a dog?

I'm sorry if the answers to these questions seem obvious to you, but I really don't get it and would love for someone to shed some light on this so that my girl can have more fun at home and not go crazy during the cold winter months 🙂