How to play this trill?

[trickybily]

I have read that the (tr) sign in sheet music is a trill which means changing fast two notes. My question is: which notes should I play as a trill in the following example, how many times, how fast:
https://ibb.co/GPmmNqw

[lelle]

The tr sign on a note means that the note in the score is the lower note. The upper note is the closest note above that fits in the key signature, unless otherwise indicated. My guess is either a f or an f#, depending on the key signature.

How many times, how fast, and if you should start on the upper or the lower note depends on personal taste, ability, and the style of music. But it's at least E-F(#)-E or F(#)-E-F(#)-E depending on if you start on the upper or lower note.

[trickybily]

Thank you