Step one. Download the addon/map
Step two. when it is finished scanning for viruses and stuff and appears in the thing that shows folders, programs, etc. and open "local disc", then open "Blockland", then right click addons and select explore.
step three. click and drag the addon and put it in the addons section, put it between two addon folders, it will appera at the VERY bottom, then right click, select extract all, and viola.
Hope this helps.