It sounds like you want a sort of header/footer, but on the right side of the
page instead of on top or bottom.
Try using two columns. You can make one column take up most of the page,
and the column to the right take up a narrow portion. Push the right margin
slider over almost to the edge of the page so it appears like the text is in
the margin. Tinker with the margins until it looks right.
Of course, most of the right column would be blank, but it sounds like that
is what you want?
Use a column break to force the text to break between one column and the
next. If you want to continue on with the rest of the document set up
normally, use a section break. In fact, you may want to set up your section
breaks and columns before you start entering any text, so you know that you
have it right ahead of time.