I would start by getting a good Jazz “Fake Book” There are many on the market, some more accurate than others, But most of them have the basic melody and chords to go along with.them. Then listen to some selected songs that you like. Memorize the melody. The melodies are often times very simple. Then start working with the chords. Playing the scales of the chords. Knowing the notes of the chords will allow you to begin to improvise using the melody as a guide.
I would not start out by purchasing “Jazz for Violin” (there are many books out there like this) I have found them either too limiting, or too advanced.
Also, it is very valuable to play with other people. Try to find a guitar player, keyboard player or even a bass player to play with you sometimes.