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I am a non-technical user. I use LaTeX to type up stuff and that's it. What I want to do is make posters like from this website. http://www.brian-amberg.de/uni/poster/
I think this gives me a new "class". How can I make it so that when I open TeXShop I can just type in the document class and then make my poster? I am pulling out my hair trying to find how to install this "class"!