Here's what I used to duck tape together a prototype using ruby on rails. If you're looking for a dev cofounder I recommend building an app (ideally the prototype for your idea), no matter how much tech experience you have. It's an invaluable knowledge set to have if you're trying to build a tech company, recruit tech talent, and let people know you're serious about hustling. I would argue it's a necessity.
Rails + CSS:
I found the videos most helpful but the pdf can be good to reference. You pick up CSS basics along the way as well.
Guide to Ruby as a Language:
Pretty light and playful. Worth skimming.
Specific Feature Tutorials:
Great follow-along videos for building almost any feature in rails.
Amazing Q+A for programming issues.
Good for looking up CSS how-to's.