Instructions
Navigate to the "Terraria" maps section of the Curse website (link in Resources) and then click a category of maps that interest you.
Click the name of a map in the category that you are interested in to view a description of the map.
Click the "Download Now" button to download the map to your computer.
Highlight the "Terraria" file that you have downloaded and press "Ctrl-X" to cut it. The file is in archive form and must be placed in the correct folder and extracted before you can use it in the game.
Navigate to the "My Games" folder in your "Documents" folder and then open the "Terraria" folder.
Open the "Worlds" folder inside the "Terraria" folder and then press "Ctrl-V" to paste the downloaded archive.
Click the "Compressed Folder Tools" tab with the archive selected and then click "Extract all" to extract the archive contents. Alternatively, right-click the archive file and select "Extract All" from the context menu.
Launch Terraria and click "Single Player" from the title screen.
Select the character that you want to play as and then click the name of the map that you have downloaded to start playing.