First, the standard and common name for "a circular planetary ring" is "an orbit".


Second, to answer first question, divide    radians  (full angle, or complete angle, or one full rotation angle) by 190000 hours.


And finally, the linear velocity is the circumference of the circle (= the length of the orbit)   =  kilometers,

divided by the time of one rotation 190000 hours.


You do all needed calculations.