This simiplified version of the Brahms theme is written in C Major. There are four beats to the measure, and the song starts on the count of 4.
Observe the tied notes in measures 9-11, 15-16, 25-27, and the last measure. The second note of the tied notes is not played again.
The first note is G below middle C written as a leger line.
Note: The chord in measure 16 designated as D, should be D minor.