Hi. Don't get your hammy a friend
Unless you plan to keep them in completely separate cages and never let them meet out of the cage. They are likely to fight to the death or one bully the other so it ends up not getting any food and having a lot of stress.
It is only very experienced owners who can sometimes introduce a new dwarf hamster to an existing one - and that is not common. The rule of thumb is that if they have always been together - eg two sisters or two brothers, or a Father/son, Mother/daughter - then they can live together. But even then they often end up fighting and needing separating so you would always need a spare cage then.
Hamsters are naturally territorial and even dwarf hamsters that have lived together happily since birth can fall out when their hormones start to kick in and they're no longer babies.
As the others say, your hamster doesn't need a friend
They bond well with a human though. Your hamster will be happy if you do the following:
1) Give them enough space in a cage with lots of substrate to dig in and bury hoards in - at least 4" deep - 6" is ideal or more if you have a tank.
2) Give them plenty of enrichment in the cage - that includes enough substrate but also includes variety - toys, hidey places, a house big enough to build a good sized nest in (especially for winter) that is dark inside, a shelf or platform they can sit under or climb onto for somewhere else to go. House that is open underneath and sat on top of the substrate is best so they can burrow down and bury hoards under their nest.
3) A good hamster mix and a bit of fresh veg daily
4) Out of cage time in a safe area a few times a week.
5) Don't do big cleanouts weekly. Spot cleaning is best and only then change the substrate after 8 weeks or more - replacing some of the old so it still smells familiar.
6) Don't remove their hoard or nest - it's the most important thing to them and best left well alone. If either are pee'd in you may have to remove most of it when spot cleaning, but always replace any hoard with new food in exactly the same place and put new nesting material out so they can rebuild the nest (plain white toilet paper torn into strips is best).
All of those allow the hamster to have normal behaviours so they're happier and don't get stressed. They need a place to retreat that's dark (the house) and tend to bury hoards under their nest in the house and also like to forage for food and nesting materials. So paper nesting material can just be left in a pile in the cage somewhere and the hammy will take it back to the nest and build a nest. Scattering a bit of food as well as putting it in the food bowl goes down well as then they can forage for that.
Also giving them a sand bath or litter tray with sand in in the cage is a good idea - they will often use that as a toilet which helps keep the cage clean - you just scoop out the wet sand or change the sand now and then (needs to be Chinchilla bathing sand).
When setting up the cage with toys etc it's important it isn't too open and exposed from above - some kind of overhead cover helps them feel more secure - hence a shelf or platform is a good idea or things like plastic sputniks that hang from the roof - also larger tunnels on the floor and hidey places like little cardboard boxes (eg tissue box) etc to dive into.