\lyricsto
above the staff definition, because at that point the voice to which the lyrics are assigned has not been created. Thus, you have to insert an empty dummy definition
\new Lyrics = "lyricsname" { s4 } \new Staff = "staffname" << .... >>and do the actual lyrics assignment later:
\context Lyrics = "lyricsname" \lyricsto "voicename" \lyricsdefinition
This snippet is a simple example how to add lyrics above and/or below the staff.