When recording music you typically have some sort of MIDI instrument connected to the soundcard installed in your computer. The software records what you play on the keyboard and stores it with the document.
During normal recording you must keep time with the music. If you've added tempo markings you'll need to play along with the changing tempo, for example. The metronome sounds out beats to help you play at the correct tempo -- you can also disable the metronome if you wish. You can use lead-in measures to count out a few bars of introduction before the actual recording begins so you can get a feel for what the beat is.
There are two additional special recording modes you can use to assist you in creating your music. Step recording isUsed when you don't want to have to play in time with the music (or metronome). Loop recording isUsed when you want to try out different "takes" of a section of your music.
Click on one of the topics below for details about each aspect of recording: