Maps in Minecraft are the interactive spaces for you to play in. They are all made out of cubes.
1. First, go to any website which maps are uploaded to and download one you like the look of. It should be in .zip format.
2. Find the file you downloaded and extract it using WinZip or 7-Zip. Copy the folder that has been extracted.
3. Start up the Minecraft Launcher, and click Launch Options on the top right corner. Then click the profile that you are willing to use. Then click Open Game Dir, and the .minecraft folder should appear.
4. Paste your map file into the saves folder and start Minecraft as normal. The world should appear and you can play the map.