So, you practice an instrument, or use some music software. You've started using HighC, and, while you feel it looks cool, you can't seem to get the grip of it, or it appears somewhat tedious to create what you want. This page is for you.
As you'll have noticed, for instance by checking out the
andantino sample, traditional western
music looks in HighC like mechanical-organ tapes. This means that if you want to stick
to the type of music you're used to, you'll have to somehow respect this model,
and have most of your pieces consist of strings of short, horizontal and
properly spread sounds (meaning they should respect the tempo and intervals
of your tunes). To help you with respecting this constraint, turn on the "Snap
to pitch" 
and/or "Snap to time" buttons. Don't forget also that when holding the Shift key
down while creating or moving sounds, the pitch is forced to remain
constant, producing the type of constant-pitch notes we're all used to hear.
Don't forget also the View > Time Scale menu to set the tempo of your
piece.
The shortcuts and editing methods of HighC have been designed to let you create those sorts of scores very rapidly. See below on some additional hints to transcribe a score easily. Also, don't forget you can enter chords and sequences easily in HighC by using a MID keyboard.
Perhaps you will want to create a short loop of just a few seconds to start with, such as noiseLoop. As its name indicates, this is not really a composition, but rather the basis for a rhythmic loop.
Next, you will probably want to take advantage of the specific nature of HighC. HighC is really cool for 2 things: creating long-evolving glissandi, and creating tight clusters of multiples notes spread over an octave or less. I suggest for a start you create some standard rhythmic and harmonic patterns, to provide a consistent base line for your piece, then introduce some more "wild-sounding" tracks to check out how they sound.
When you create some odd-sounding parts, such as a long glissandi, it is crucial that you check the tuning of the curves you've created, to control the dissonances they introduce. One easy way to create "quite in tune" glissandi parts is to make sure the key points of a glissando sound (beginning, maximum, minimum and end) are aligned with the tune you're playing in, for instance, the dominant or tonic notes of your scale.
When you've created a sound that you like, using copy/paste and then transposing it in pitch or in time is a good way to stay "harmonious" while creating long pieces or nice effects. See the waves1 sample for instance: it consists in 5 "glissando clusters" that follow a harmonic progression but are placed along traditional music intervals.
In other words, respect the natural intervals of music, octave and 5th for instance, when you create long sounds, glissandi and clusters. However, don't feel like you need to be anal in the precision with which you draw: a large part of the power of the parall sample comes from the slight time shifts between the start of each ascending and descending wave.
After you've created some loops and a few sounds that may have raised your curiosity enough, comes an almost philosophical question: are you creating a visual piece that can be heard, or transcribing what you want to hear using visual means ? HighC's intention is to raise this question, and leave it open. If you start from a music background, you will consider HighC most likely as a tool for composing music. Yet, the visual nature of your transcriptions can, or at least should, help you and guide you in making your approach at music composition evolve. Basing some of your decisions on the graphical aspect of the score can be a way to solve the "blank-page" dilemma or provide solutions on how to resolve some parts your have trouble dealing with.
The regressing_line sample is a typical example of such a composition that is guided by the visual aspect of the piece. It started more as a pure drawing, the long descending line, upon which rhythm patterns and harmonic figures were added.
When reaching this point, you'll know much more than myself what you can or want to do with HighC. The next section covers how to do it rapidly and easily.