You have to use doggie toothpaste, NOT HUMAN, which you can find at the petstore. Introduce the dental care to the pup gradually (e.g. let the pup taste some from your finger, get them used to you touching their mouth/teeth by running your finger along side their mouth, etc.). Make sure you give treats and praise when they let you do these things.
We bought a baby toothbrush for Rylie because all the petstore ones were WAY too big for her tiny mouth, just be careful because some human toothbrushes are too hard for puppy teeth.
Rylie now LOVES getting her teeth brushed. She literally jumps up on the couch when she sees me getting everything ready with her little tail wagging. Just make sure to make it a positive experience from the beginning and you won't need to fight them to get it done!
Good luck!