Hi Ivan, I think everyone will agree you'll need an instructor/mentor, the thought of training a single young dog without one is pretty daunting (unless you've been doing it for a long time). I started the thread that Mary Beth linked to (thanks!
) to track my progress with my second dog.
The instructor I go to has multiple different groups of sheep that help the dog learn and progress. "Test"/ "Heavy" sheep (not very reactive, knee-knockers, predictable) to start out with, then "Trial" sheep (moderately more reactive) and then Light / wilder sheep, ewes with lambs, lambs, new sheep not accustomed to being worked by a dog, etc. things that you'd encounter in a real farming venue, that pose additional challenges. Trying to start a dog on a mixed, wilder group of sheep (or lambs) will be incredibly difficult.... like throwing a kid into the ocean on their first day of swimming lessons.
There's no substitute for an instructor, but out of all the books I've read, these are my favorites that I've kept on my bookshelf as resources.
Herding Dogs: Progressive Training http://www.amazon.com/Herding-Dogs-Progressive-Vergil-Holland/dp/0876056443/ref=sr_1_1?ie=UTF8&qid=1458580080&sr=8-1&keywords=herding+dogs+progressive+training
Stockdog Savvy http://www.amazon.com/Stockdog-Savvy-Jeanne-Joy-Hartnagle-Taylor/dp/1577791061/ref=sr_1_1?ie=UTF8&qid=1458580093&sr=8-1&keywords=stockdog+savvy
Teaching the Rules of the Hunt: an Introduction to Herding http://www.amazon.com/Teaching-Rules-Hunt-Introduction-Herding/dp/0578092530/ref=sr_1_1?ie=UTF8&qid=1458580111&sr=8-1&keywords=teaching+the+rules+of+the+hunt