View source for Template:Note

<includeonly><div class="tt1_graynote">{{{1}}}</div></includeonly><noinclude>

It looks like this:
{{note|This is some example text that would be in a note. You will note that if you type for long enough, it will wrap around the edge of the page.}} 

It takes a single parameter that is the contents of the note. Use in the middle of a paragraph at your own peril.

[[Category:Templates]]</noinclude>