Tune the violin with a tuner or a piano. Turning the pegs at the scroll (top) of the violin or the smaller "fine-tuners" clockwise will tighten and raise the pitch of each string, while turning them counterclockwise will loosen and lower the pitch of a string. You must match the pitch precisely with its proper note (tune an A-string to the A of a piano or tuner).
Hold the violin between the left shoulder and the chin in a way that leaves no need to support the instrument with your hand. A shoulder rest will likely be necessary; it attaches to the bottom of the instrument to adjust for comfort while holding the violin properly.
Place your left hand toward the scroll (top end). Your left thumb will place gently, not gripping, the left side of the neck of the violin. Your fingers should curve over the top of the black fingerboard. Avoid placing your palm against the neck of the instrument, because doing so makes several techniques--such as vibrato and shifting--impossible, and it strains your hand. Your wrist should align with your arm.
Hold the bow. Grip the "frog," or bottom end of the stick, by placing your thumb in the nook, with your middle and ring finger above the wood grasping the stick, curving over it. Your forefinger will rest a larger distance away from your middle two fingers on its side, and your little finger will rest on its tip toward the end of the bow. With much training, the bow grip must take advantage of the joints of the fingers, providing a firm but flexible "springy" grip, with most of the force in the middle and forefingers and the stabilizing in the forefinger and little finger.
Place your bow on the string. The bow hair must always (with rare exception) move perfectly perpendicularly across the strings between the "bridge" (which is holding the strings) and the black fingerboard. To make sound, stroke the bow across the string; with no fingers placed on the fingerboard (left hand), you will hear the sound of an "open string," such as an "A" on an A-string.
Stroke the bow across the string, always making sure the bow travels straight up and down while moving. Proper, straight bowing requires not moving your upper arm until using the bottom part of the bow. Your wrist and fingers must also remain flexible, for accommodating a proper bow stroke, among many possible kinds of strokes for different sorts of sounds (for example, more pressure and longer strokes cause more sound).
Place your fingers of your left hand on the fingerboard to make the sound of different notes. On an A-string, for example, placing your first finger down in the proper place will cause the next note (B) to sound. Knowing the placement of each note takes years to fully understand, on the principle of shortening the strings to raise pitch.