Some we make ourselves, others are freebies from variouis scrapping sites, stores or blogs, and others are from kits we purchased from the same sites, or online stores. If you are just starting out, a GREAT place to visit is
www.mousescrappers.com They are a forum just like this one, but they are ALL about scrappbooking. They run challenges, that offer prizes for participating, or in template challenges, you can download a free template to use to participate in that challenge. It's through mousescrappers that I've been able to complete so many of my Disney Pages over the past 6 months. Lots of tutorials and tips to be found there too.

Google these sites to find them, they offer digital freebies
Persnickety Prints
The Daily Digi (offer free kits each month, with one piece of the kit emailed to you each day of the month till complete)
And some blogs by Digital Designers offer freebies, or even their facebook pages, you can also visit their stores and see all the wonderful kits they create:
KellyBell
Scrapping With Liz
Brittish Designs
Or just google Digital Scrappbooking freebies