Well, at least you're just training for the 100 and 200 right now instead of the 200 and 400.
I can remember parts of our sprint workouts back in HS, but I don't remember us being grouped up into specific events like 100, 200, or 400. It was kind of all in 1. I hear this is how it's often done at the HS level but it's much more focused at the collegiate level.
Our coach seemed to be very technical and I came away from it with a good idea of understanding (I think) of what he was trying to get across. We had some decent sprinters in our city. I can remember most of everything but the amount of volume of sprints we did.
Do you have any experience in sprinting or know anyone locally who could at least run you through the basics drills and how to start and get out of the blocks?
Maybe, just go check out the local HS or college or ask their coaches.
Working 25's and 50's sounds like a good idea right now.
My friend who sprinted at a Jr. College, he's somewhere on PM said volume of around 250y/m was about right after looking at the thread. So either 5x50 or 10x25 for 100m sprinters. For 200m, there would probably be something similar except some 100's and 150's in there as would 75's be in there for 100m runners.
Right now, I work 25's, typically sprint, then walk back and do 3 repetitions and wait for about 2-3 minutes before starting another round. This is just speed work programmed into my S&C for gymnastics, however. I can do about 3 this way before a rest is a good idea. Generally about 10-15 sprints. in volume so 3-5 rounds. It sort of depends how many 1 leg sprint-jump-runs I do.
For simply doing 100's during sprint workouts, I noticed walking that distance was ok. I think walking twice that distance would have been more rest. Actually, probably just resting would have been much better.
For 200's, simply walking another 200 was the same which took about 2.5 minutes. Again, if I did it again, I'd omit the walking that distance, walk a short bit and just rest in between.