I don't understand how to play the trills and mordents in Bach's BWV 926. I don't know how to play them in general. Could somebody please help me?
Baroque trills generally start on the upper note of the trill and continue for the length of the note. Mordents are a single rapid alternation of the note above/below and are differentiated by a short squiggle. An upper mordent, where the single alternation is above, looks like this:
It starts off with an inverted mordent (mordent sign with a line through it) on D, so you play a rapid D, C# and D, starting on the beat. The sharp sign next to the mordent sign indicates that the C is played as a C#.
With the regular mordents (as in b.16) you play the rapid three notes on the given note, next note up, and back to the given note, always starting on the beat. Note that in b.21 you play a C# then a B natural, and back to a C#.
My copy doesn't have any trills but you could do one five bars before the end on the 2nd beat in the R.H., starting on F, then E,F,E,F etc, ending it on an E.