Row, row, row your boat is a very simple melody. You can download a free copy of the melody from www.sheetmusicdigital.com.
C, c, c, d, e, e, d, e, f, g. Ccc, ggg, eee, ccc, g, f, e, d, c
row row row your boat gently down the stream merrily merrily merrily merrily life is but a dream
It depends on the arrangement. It could be in 2/4, 4/4, or even 6/8 time.