I'm in the process of training my 3 month old lab for sheds. I started my pup BB, by introducing a shed to her everytime before she ate.....held shed up to her nose and stated "shed". I did that for the first few weeks that I got her home. I then started stashing sheds around the house and telling her to "find the shed". She knew what shed meant and thus hunted around till she found them....lots of praise and a treat to reinforce the find. I continued that for a few weeks and started to hide them under rags or sheets so she had to use her nose. Last week I took a few sheds that I put into plastic bags when I found them last winter (no human scent) and placed them in the tall grass around the house. Leading her downwind of the sheds I said "find the shed" and sure enough she followed her nose right to them.
I'm not an expert shed dog trainer...basically just figuring it out as I go, but what i've been doing seems to be working.
I know that there is a training video that Is produced by the fella from missouri that has made shed dog's famous....can't remember his name but it's supposed to be a quality training video.