To record notes in MIDI format (similar to sheet music) you will need a MIDI keyboard, like this:

Click here to choose the MIDI keyboard best for you.

You can also use a MIDI piano (which usually has weighted keys and so feels much more like a piano - but costs more), such as this:

Click here to choose the MIDI piano best for you.

Or a MIDI controller like this one (which does not have speakers and so requires it to be hooked up to a MIDI synthesizer, such as a PC computer to produce music):

Click here to choose the MIDI controller best for you.

Some MIDI keyboards come with their own USB adapter cable to plug into your computer. Others require you to buy a separate USB MIDI cable.

Recording in MIDI format is like recording sheet music - it records the notes with their durations and volume. It also can record in a variety of instruments (and the instruments played can easily be changed after recording). After recording, you can easily edit and print out your sheet music.

You can record music using your PC and MIDI keyboard with Music MasterWorks (click here for free 35 day trial). In Music Masterworks, select the record button (no need to select a device, it will by default record from all MIDI input devices that are available). Play your keyboard and you will see the 'Recording...' message change to 'Receiving MIDI Messages...'. When you are finished hit the 'Done' button. You will then be given several choices, including where you want the recorded section to be placed (it will default to the play/record line), and how you want it mixed into your existing music.