Shed Manual in Centre for Alternative Technology's Christmas catalogue

Here's what the fine people at CAT say about it:

Covering topics such as getting started, shed styles, materials, foundations, hardware and finishing, The Haynes Shed Owners' Building Manual provides step-by-step instructions and wide-covering advice on all aspects of planning and building sheds. Written by two shed experts, it's for the enthusiastic DIYer and those considering taking on a project.

Buy early, buy often, either via their catalogue or from their website.