My old fan had 3 wire brown orange and black so the new fan only has white and black so what do you do with the new wires

Old motor was probably two speed. New motor single speed. Assuming 120 volts, old motor white was neutral, black was probably high speed, orange low speed.

If you still have old motor check label. If this is gas furnace and a/c air handler combined, you probably should get two speed motor. High speed to a/c, low speed for heat.

Otherwise connect white to white, black to black.