Hi Wilson,
I hope you only bought another pedelec sensor
(or speed controller) and didn't have to buy another wheel.
Anyway, the black sensor block
(or "black blob") needs to face outwards towards the magnet ring as shown here:
It doesn't have to be in the same "12 o'clock" position shown, so fit it where it provides the best wire route.
You may need to make a small spacer block to fit between the black rectangular sensor unit and the mounting bracket if it is too far away from the magnet ring, but I suggest you try fitting the unit first and see if it works
before worrying about the spacer.
Remove the pedal crank and the bottom bracket lock ring and then tighten the lock ring to hold the sensor bracket securely in place.
Slide the magnet ring onto the spindle with the arrows facing in the same direction of rotation as the pedals
(as shown in the previous picture).If the pedelec works, there should be no need for a spacer, but if a spacer is required, it can be cut from thin wood or plastic etc.
I would apply glue or double sided sticky tape on each sides of the spacer to make sure it doesn't twist around the screw.
You would also need a slightly longer retaining screw if the block needs to be spaced a long way from the bracket.
A hot melt glue gun or epoxy glue could even be used to add a thick layer of glue between the sensor unit and the bracket to form a spacer and attach the sensor all in one go.
If you had another locking ring, you may have sufficient thread available to simply fit the sensor bracket on the outside of the existing lock ring using the extra locking ring to hold it in place, and this would also reduce the distance between the sensor and the magnet ring.
Alan