How do i control a 6 V supply output based on a 5 V input?
simulate this circuit &ndash; Schematic created using CircuitLab
Figure 1. Modified schematic.

The &quot;sinewave&quot; is PWM unless it has been filtered in some way (which you don't want in this application).
When the PWM goes high (5 V) R1 provides almost 10 mA to the base of Q1. This should be enough to drive it into saturation so that the collector (motor's negative) is pulled down to within about 0.2 V of ground.
Motors are inductive so when Q1 is switched off the current will continue to flow. D1 diverts it away from the transistor which will probably die a rapid death otherwise.

As pointed out in the comments a 2N2222 may not be adequate but we have no specifications for the motor so check that out.

From the comments:

The question says how do i get a signal that can be anywhere from 0 to 5 V to proportionally control a 6 V supply, If this controller pwm signal is 2.5v, get the 6 V supply to be 3 V etc.?


Figure 2. The effective sinewave generated by a sine-modulated PWM. Image source: Which IC produces PWM that can be filtered into sine wave?
Your PWM signal is not a sine wave. It is a series of pulses going from 0 to 5 V. It is a digital output. When it is filtered by, for example, an RC circuit you can generate a sinewave, but we don't bother for motors as their inertia and inductance smoothes out the motion adequately. Figure 2's sine is showing you the effective voltage given by the PWM.
So to answer your question, to get 3 V on the motor you switch between 0 and 6 V with a duty cycle of 50%.