This a free 300-page download of
The New Seed Starters Handbook by Nancy Bubel. (It's also available in paper book form from the usual sources.)
It's simplified enough for the beginning grower, but also has a lot of useful information for the experienced gardener.
Nancy Bubel is well-known for her books on various gardening subjects, especially
Root Cellaring: Natural Cold Storage of Fruits and Vegetables, although she has written other books on gardening and several gardening bulletins.
You can download it from here:
http://www.green-seeds.com/pdf/seed_starters.pdf Sue