The thing to do is to rub your hands together to bring the healing energy up into them. When they're warm or tingling, place them on whoever needs the healing, yourself or another person. Trust that it will work, and let your intuition tell you where to put them and how long to leave them there.
Be careful not to deplete your energy. This will happen if you do too many healings in a short space of time. You might have to experiment to find out how many you can comfortably handle in a day. If you're not setting up as a practitioner, you probably won't get that many anyway.
Depletion is not a problem with Reiki, because we're not using our own electro-magnetic energy fields; we tap into the Universal energy, which never runs out. The smart answer to the question is, if you've never learned Reiki, learn it! But you might have your own rasons for not wanting to, or for not wanting to yet. Don't let that stop you in a case of emergency, if you can't get medical help or while waiting for it to arrive. There IS something you can do to help.
Also, of course, there are many other good modalities around, and one of them might suit you better. Again, many of them don't tap into the Universal energy, so you would have to use commonsense in looking after yourself as well as your clients. But you could always add Reiki later, which would enhance whatever else you might do. And if not — they are still good modalities.