Violin players.please help?

Yes, If a scale is in "D" then the scale will start with D. You also need to know if it is major of minor, because that is important. If you want to improvise, then you simply need to play the note that are in that scale and no others as a beginning improviser. If you are improvising with others try to stick with the 1st, 3rd, and 5th notes in a scale. This will make it easier for someone else to solo over you. Also, try to avoid the 7th note in the scale unless you plan on playing the 1st note right after it. Trust me, this will make it sound better and "more right". I hope this helps you.