I figured it out and im am telling how for ppl who want to know in the future.
Step1, go to the Add-ons forum.
Step2, Find a thread of an addon you would like
Step3, The first post will have a download link to it, click
Step4, It's on you desktop. Open the blockland folder and put it in Add-ons.
If there is a folder with it, i don't know what it will do if you put it in addons, but go ahead.
My first add-on was a map; Slate 2.
FINALLY