Download the trial version of Pizzicato from its website, or launch your own preferred software. Examples of other possible software include Finale and Sibelius. According to Arpegemusique.com, Pizzicato ranges from $22 for the basic version to $430 for the professional version, so it is wise to try the application out before buying.
Launch the application and create a new, blank song. You should be presented with an empty staff to fill.
Click one of the symbols displayed on the toolbar for a note or rest, then click where you would like it to be placed on the staff. The note will appear where you placed it. According to Arpegemusique.com, Pizzicato will automatically adjust note spacing and note beams for you, giving you a professional look. If you have a keyboard with a MIDI output, you can use a MIDI-to-USB cable to directly connect a keyboard to your computer. Pizzicato can then be set up to record what you play, making note input much faster.
Adjust the clef, key, time signature and instruments for your piece. You can change these at any point in the score, so be creative, and don't be afraid to experiment. Continue fine-tuning your score by adding dynamics, expression marks, or experimenting with the many different options.
Share your score, either by printing it out or sharing it on Pizzicato's website. There are other sites as well for sharing music, including Iwritethemusic.com. Seek feedback from fellow composers and musicians to help your composition techniques improve.