If your vet is not available in the next few hours and your puppy's diarrhea is only mild, there are a few things you can do to care for her while you wait. First, ensure your puppy can freely access clean water. Diarrhea can lead to lots of water loss and your pup needs to stay hydrated – so try getting her to drink. You can also try watery broth to entice her, but use natural broth rather than a salty pre-packaged product. Try to get some veterinary advice on the phone regarding what electrolyte solutions you might be able to add to her water bowl.
You can also take your puppy off her regular kibble and switch to simple boiled/steamed chicken and plain rice. This is easy on her little tummy, and will keep her going until it's time to head to the vet!