Please be cautious with moving or modifying your save files. It is advised that you make a backup before you perform any actions in this folder. You can back up your files by copying them and storing them in another folder or on a USB drive.
Start by finding your saves folder. You can find all Minecraft folders, including the saves folder, by going in to the game launcher:
- Open the Minecraft launcher and log in. Click "Launch options", and then click the launcher configuration you are running (the default is "Latest release"). Locate the "Game directory" selection, and click the little green arrow to the right of it. A new window will open containing your Minecraft folder. When you open the saves folder you will see all your saved worlds in different folders
- Place the world folder(s) that you want to transfer onto a portable storage device, file sharing software or cloud computing service.
- Once the files are ready to be transferred, place them in the new computer's saves folder and they will be available in your list of singleplayer worlds.