For a 15 minute video demonstration go here.
Running meridian lines is standard, relatively simple entry level Qigong/Chi Gung. It will have beneficial effects whether of not you can feel energy but as you learn to discern and direct the chi the benefit will be much greater.
Chinese medical theory states that health is a function of how balanced the flow of chi is in the energy grid. Thus, exercises to clear and balance the lines in the grid are known as Medical Qigong. This network of several thousand lines is considered more basic than physics and chemistry, the bottom lines for western medicine. Acupuncture uses 14 of these lines while basic chi gung uses just a handful of the major ones.
An imbalanced flow means excesses and deficiencies and the main way to restore balance is to clear out the constrictions that create backups upstream and shortages downstream, much like removing debris from an irrigation system. (It is not really necessary to know flow directions since all lines flow in both directions.) The basic technique is simply a form of Dissolving, melting away congestion in the energy channels. (There is also the Yang method where you fill up empty channels, or blast through blockages but like most Yang practices there are risks of creating more blockages if you do not understand the balance of force and relaxation, so it is far better to learn Yin very well first.)
Ultimately you want to be able to clear channels with your mind alone but most people, even those with years of experience, find it easier to use their hands. Begin by sitting comfortably with one arm resting on your lap, palm up, so that it feels lightly stretched out by gravity and there is a little space in the armpit. Point the fingertips of your other hand at your sternum, near the heart, about 4 inches out from the skin. Keeping this distance move out to the shoulder and down the length of the resting arm along the inner (yin) surface to the fingers and at least 4 inches beyond. You want to feel as though the active hand is promoting the further relaxation of the passive arm.
Try to establish some sort of energetic connection between your fingertips and your skin. Use your intention to project energy. Try turning it on and off and see if the passive arm can feel anything. The feeling can take many forms such as heat, wind, water, electricity, melting, etc. You might try pulling instead of projecting as though you were dragging a rake down your arm. Stay relaxed, acting without force. Attempting to do this with your muscles would be counterproductive and missing the point. The reason you stay about 4 inches out from the skin is that this is the approximate boundary of the etheric field which governs the physical body. If you can feel more sensations by working from a greater distance do so. However the further fields are more subtle by nature and it could be harder to send your your energy across more space.
There a few variations you could try once you get the basic idea. Fingertips have the ability to focus on specific lines, the main one running down the center of the inner arm. Two fingers can be more specific and powerful: touch the thumb and last 2 fingers together, thus funneling the energy of 5 into 2. (This is called “sword fingers”.) Conversely, if you wanted to effect the whole arm generally you could use your palm, projecting or pulling more diffusely.
After tracing the arms which are naturally more sensitive than the rest of the body you could proceed to the other major meridians. If you draw a human stick figure you will have the core meridians: head & torso, arms and legs. When you trace the legs you will either need to lean forward as you descend to the feet or if for some reason you can’t lean, project your energy to the feet and a little beyond. In addition there are the main left and right channels: Begin at the top of the head and descend through the ears, down the sides of the neck to the small depression under the collar bones (called the “shoulder’s nest” due to it’s bird egg size). From here they run down through the breasts to the hip joints and are lie very close to the central channels down the inside legs.
There are lines that run on the skin and lines that run through deeper layers of the body. For example the central channel of the torso has 11 layers from skin to the central axis. With practice you can learn to project through to your back where your hands cannot reach. As you are able to access the deeper levels the beneficial effects will be much greater. In the arms and legs the central channels run through the bone marrow. (By the time you get here you will most likely have graduated beyond the need to use your hands and instead rely on your mind alone.) It is said that if you can access the central torso channel (what I call central central) you will from there be able to cure all your diseases. This channel is what connects you to the cosmos is therefore integral to spiritual practices.