24v DC Motor Controller HELP!!

Thank you f4b and Grumpy_mike. I think I have now got an appropriate schematic so thank you.

In regards to the diode to use. What would be suitable/cost effective a silicon or schottkey diode.

I was thinking about a 3A 1000V Unidirectional Silicon Diode or 6A alternative? I've tried to learn about diodes and their spec requirements however still struggling with it.

Cheers.