Walk her around a bit, and let her drink. If massaging your horse is something you would like to do on a continuing basis, I'd suggest two things. The first is to purchase a book with good illustrations of equine anatomy, so that you can learn to follow the muscle fiber direction as you work, and secondly, spend as much time as you can watching horses groom each other. Some offer the training only to veterinarians or vet techs, to qualified body workers in the human realm, or to people with a background in physical therapy or medicine. Others accept any student who wants to offer this work to horses.
Some schools consist of weekend workshops, and some last more than a year.
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