stream tracer and seed

Hello everyone,

I am trying to make a stream tracer plot for a vector field.

However, I tried changing position of the 3D widget a few times on the UI, but nothing show up after I click apply. Actually, I am not even sure the plot is doable and how to determine the where is the starting point of integration. Can anyone give me suggestion how to make stream tracer plot or where can I learn more knowledge behind stream tracer plot and seed? Thank you very much.