well, once you download your add-on, (make sure its finished downloading) something should appear on your desktop that will say the add-ons name. drag that item into your applications folder, then drag it into your Blockland folder, then drag it in the add-ons folder. then once you've done that, play Blockland. click on start game, then click on add-ons scroll down or up untill you see the add-on you downloaded, click on it. (you will know you clicked on it if the checkbox has a check in it). now you dont have to start a game for the add-on to work, if you clicked it, it would work if you join a game to!