You just go to the site.
I’m able to get to it from here without any problem. What you get is the abstract and then when you click on it, you get the full paper (usually in PDF), instead of the abstract.
The full paper is what the science paper delivery companies are charging money for and this site is making available for free. It’s not legal right now, although she is fighting to make it legal.
If the site is not available in your country, you could probably use a proxy server. I don’t really have a need for it because anything I want to know in a science paper shows up in the abstract. But for students and working scientists, this is an amazing resource for them.