That's killer crook, gonna check those out, here's hoping! You know, I wish I was good enough to repurposed used wood. There's tons down here due to hurricane, but my skills are so limited that I need to be told every little step
You will do fine. I have never built anything before. I had a 100+ year old crooked coop to work with. It's still old and crooked, but super sturdy. I used old scraps out of the barn to patch here, seal holes there. It's pretty funky looking and far from perfect, but the chickens like it just fine and they are safe. I've been adding "features" here and there. I honestly think that building a new coop from scratch would have been far easier. You will do fine -- don't be too critical of yourself. I think you'll be happily surprised at what you will accomplish.
I just googled "free chicken coop plans" and came up with these. Take a look. Some link didn't have truly free plans, but I checked some of these.
https://thefrugalchicken.com/diy-chicken-coop-plans-free/ (55 DIY coops)
https://www.howtoplans.org/chicken-coop-plans/
https://modernfarmer.com/2015/09/how-to-build-a-chicken-coop/