hi.
not familar with your model but there is normally a lever that you need to pull
this will pull the front wheel toward the base plate and allow you to take the belt off
to replace the belt do the opposite BUT make sure that you align the arrows on the underside of the belt so that it travels in the right direction.
there should also be a tension knob to adjust the belt when in motion. ie too far to the left or right (belt falling off or cutting into the housing.
make sure you buy the right belt. different lengths and widths
good luck
ps a quick google suggests belt are 75 X 533mm (grit number up to you)
The belt on and allow you to allow you to stay in there should also be an adjustment on and press the belt to.