The information below is taken from my Intro to Playing Melody E-book (page 4).  This handout has five important pieces of information for the individual who wishes to play melody.  Starting on the top left, there is graphic of the ukulele fingerboard (fretboard), identifying the numbered frets and strings. 

To the right of that is basic information about music notation, the names and time values of notes, how long each note is held.

Below the Fingerboard Chart is a representation of the Treble Clef.  The standard ukulele is tuned to notes no lower than middle C.  That means that melody notes will be played from the treble clef or a lead sheet. It is not necessary to learn notes on the Bass Clef.  Notes that appear on a line or space of the treble clef are assigned a name that will correspond to the notes on the ukulele.

Beneath the Treble Clef are rest symbols and their time values.  A rest symbol indicates how long to pause between notes.  Chords may be played during the rests.

The last graphic provides a complete treble clef with note names.  Under each note is the string and fret numbers where that note is located on a standard ukulele tuned to GCEA.