To use blank sheet music paper, print a sheet from the staff paper maker, choosing a single staff for one instrument or a grand staff for piano, and setting how many systems fit the page. Then add your clef and key signature at the start of each line and write your notes along the five lines and spaces.
Manuscript paper is just a clean grid of staves. The choices that matter are the staff type and how many fit the page, because those decide whether your music has room to breathe.
Choose single or grand staff
A single staff is five lines for one melodic part: a flute, a voice, a guitar line. Pick this when you are sketching a tune or writing for one instrument.
A grand staff joins two five-line staves with a brace, the treble for the right hand and the bass for the left. This is what piano music uses, so choose it whenever both hands need notating together. The staff paper maker draws the brace and bar for you.
Fit the right number of systems
How many staves belong on a page depends on how busy your music is. A simple melody with a few notes per bar fits comfortably with many staves to a page. Dense writing with chords, accidentals and fast runs needs taller, more spread-out staves so the notes do not collide.
If in doubt, print fewer and larger. Cramped staff paper is frustrating to write on, and you can always start a second page.
Add the clef and start writing
If you write for the same instrument every time, turn the clef on so it prints at the start of each staff. If you want all-purpose paper, leave it off and add the clef, key and time signature by hand at the head of each line.
Then write. Place note heads on the lines and in the spaces, and use the bar lines you draw to group the beats. Print at 100% scale on the staff paper maker so the staves stay an even, comfortable size across the whole page.