To get add-ons:
1) Right click Blockland
2)click "properties"
3)Click "find target"
4)doubleclick the Add-Ons folder
5)once downloading the addon, put it in the add-ons folder
6)start Blockland
7)start a game
8)right above the server name will be a bar with a button that says "add-ons"
9)click it and make sure to enable the add-ons
10)start the game.
For further questions, post in the help desk.