Here I go about to roast my own coffee.

roast small quantities google "Roasting coffee beans with popcorn popper"

Read what it says about "first crack" and "second crack"

you can listen to what the beans are doing most of the time.

good luck. you are now onto the path toward spending a few hundred dollars to roast beans the right way.

That is one option, he might be on the highway to a local roaster for a retail bit of business.

My Home Roasting Post with Pictures.

For what it's worth, I eventually burnt up my $14 roaster and dropped $150 on a unit made for it. The quality is so much better, especially for espresso. Green beans are in the $6 per pound range, and I only roast what I need for a few days. I have zero waste on stale beans now. The varieties are endless, and the flavor profile changes greatly on each individual bean by varying the roast darkness.