The OBI tells the pilot where his aircraft is in relation to the track
that he has selected which runs through the VOR. In your example the pilot has
selected a track of 190o - imagine yourself standing on this track
and looking in the direction of 190o. It is fairly obvious that if
the aircraft position lies in the sector between
radials 100 and 280 (lines at right angles to the selected track) then it has
gone beyond the VOR. Secondly, full scale angular deflection on an OBI is 10
degrees. Therefore if the aircraft is within 10o of the 190 radial
(or the 010 radial - ie the reciprocal) the needle on the OBI would show the
precise angular deviation. In your example the aircraft is on the 255 radial
(ie 65o of displacement) and therefore the needle would fully
deflect to the left. In other words as you look in the direction 190o
the aircraft is to the right of that track, and therefore needs to fly left to
become established.
Note that the OBI takes no account of aircraft heading!