DC voltage measurements:
Examples of how to make DC voltage measurements are show in the two diagrams below. In both cases, the red and black test leads are connected to the '+' and '-' sockets respectively.
In the first diagram, the range selector is set to DC, V, 50V. The pointer is reading just less than 45 on the range that has 50 as its full-scale indication (note that there are three calibrated voltage scales with maximum indications of 10V, 50V and 250V respectively). The reading indicated is thus 45V, approximately.
In the second diagram, the range selector is set to DC, V, 250V. The pointer is positioned midway between the 50 and 100 scale markings and this indicates a voltage reading of 75V.