You don't necessarily have "free" ebook copies, but rather you can set up a coupon in your Bookshop page that makes the book free to purchase.
You can create a coupon at any time in your account under Bookshop Manager and then Coupons
You can also send free copies of your eBook to people by logging into your BookBaby account, clicking "my books" then "view files". Choose which file you need to download, then you can attach that file to an email and send it to whomever you'd like.