Music layout in ABC is as intuitive as it can be. A row of text is rendered as a row of music.
X: 1 CD EG G2 A2 | CC DD EE FF A2 G2 FE DC | CC DD E2 C2 CD
Also, as you might have noticed, note groupings are computed directly from the text: two close letters means that the note is grouped.
So you can have groups:
X: 1 CDEF DE FG
Or separate notes:
X: 1 C D E F D E F G
Very intuitive, isn’t it?