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A page of sheet music is made up of notes and rests printed on five parallel lines and the spaces in between them, which is called the staff. The lines and spaces are counted from the bottom to the top, meaning the higher-pitched notes will be higher up on the staff. The staff can be in either bass or treble clef, which will be marked at the left-most point on each line of the staff. The clef marker will tell you which line corresponds to which set of notes:   In the treble clef, also known as "G clef," you'll notice a sign a bit like the ampersand (&), printed on the left side of each staff. This is the most common clef for sheet music. Guitar, trumpet, saxophone and most higher-register instruments will be printed on treble clef. The notes, starting on the bottom line and going to the top line, are E, G, B, D, and F. The notes in the spaces between the lines, starting with the space between the first and second, are F, A, C, and E.  In the bass clef you'll notice a sign that looks a bit like a curved number "7" to the left of each line of the staff. The bass clef is used for instruments in the lower register, like trombone, bass guitar, and tuba. Starting with the bottom, or first line, the notes ascend G, B, D, F, and A. In the spaces are A, C, E, and G, from the bottom to the top.  The tenor clef is used for choral works. It looks like the treble clef but with a little number 8 under it. It reads just like the treble clef but sounds an octave lower. The time signatures reforest to the number of notes and beats in each measure on the staff. On the staff, measures will be separated by periodic vertical lines, separating the staff into little chunks of notes. Just to the right of the clef will be two numbers, one over the other, like a fraction. The top number represents the number of beats in each measure on the staff, while the bottom number represents the value of each beat in the measure. In western music, the most common time signature is 4/4 time, which means there are four beats in each measure, and one quarter-note is worth one beat. You may also see a capitol C in place of 4/4. They are the same thing, the "C" is for "common time." 6/8 time, another often used time signature, means that there are 6 beats in each measure and the 8th note gets the beat. . More information to be included at the left of each line of the staff includes any sharps (#) or flats (b) that will designate the key signature you'll follow throughout the music. A sharp takes a note up half a step, while a flat lowers it half a step. The symbols can appear incidentally throughout the piece for occasional uses, or can appear at the beginning of the piece to follow through the remainder of the song. If, for instance, you see a sharp in the first space in the treble clef, you'll know that each note that appears in that space will need to be played one half-step higher. Likewise, with flats. On the staff will be printed many different types of notes and rests. The style of note refers to the length of the note, and the placement of the note on the staff refers to the pitch of the note. Notes are made of heads, which are either dots or circles, and stems, which trail off from the head of the note, either up or down on the staff, depending on the placement of the note.   Whole notes look like ovals, and are held out for 4 quarter notes.  Half notes look like whole notes, but with a straight stem. They're held for half the length of a whole note. In 4/4 time, there would be 2 half-notes per measure.  Quarter notes have solid black heads and straight stems. In 4/4 time, there are 4 quarter notes in a measure.  Eighth notes look like quarter notes with little flags on the end of the stem. In most cases, eighth notes will be grouped together for each beat, with bars connecting the notes to signify the beat and make the music easier to read.  Rests follow similar rules. Each whole rest looks like a  black bar on the middle line of the staff, while quarter-note rests look a bit like a letter "K" in italics, building stems and flags as they break down into further divisions per beat.  A dotted note or rest means that you add half of the value of the note. For example, a dotted half note would be 3 beats and a dotted quarter would be 1 1/2. . Western musical notation is a fairly complex symbolic language that you need to understand to read first if you hope to write it. Just as you couldn't hope to write a novel without understanding to read words and sentences, you can't write sheet music if you can't read notes and rests. Before you try to write down sheet music, develop a working knowledge of:  different notes and rests the lines and spaces on the sheet rhythm markers dynamic markers key signatures Some composers compose with their pencil and paper, some compose with a guitar or a piano, and some compose with a french horn in hand. There's no right way to start writing sheet music, but it's helpful to be able to play yourself to practice out little phrases you're working on and hear how they sound. Plunking out some notes on the piano is especially useful for composers to know, since the piano is the most visual instrument--all the notes are right there, laid out before you.

Summary:
Write the clef on the staff. Write the time signature. Set the key signature Learn the different kinds of notes you'll use. Spend time learning from other scores Choose your composition instrument.