When Blizzard Beach is open, you can just take that bus to get to Winter Summerland. WSL is right there.
To get to Fantasia Gardens, you'll need to make your way to the Swan. You can take a bus from MK, DTD, or DAK to the Swan, or the boat from the Studios or the World Showcase. From there, it's a short walk to Fantasia Gardens. One note, PLEASE PLEASE PLEASE be VERY VERY VERY careful when crossing the street. Only use the designated crosswalks, and wait for traffic to clear. It's not a busy street, but it is a FAST one, and cars will NOT stop for you.