Existentialism....what exactly does it mean? Any examples of existential art?

Existensialism involves any theories on the subject/topic of existence. So people have negative existensial beliefs either positive or negative. Like one can think they exist some say they can't. I actually very much like the topic. Like the statement: Nothing can not exist. This to me is true. B/c if it exists then it's something and here we are talking about nothing so to say that there is this something which is nothing seems contradictory and so nothing can not exist. Some will say well there is the idea of nothing and so forth but then that is something still namely an idea. Now of course one NEEDS the idea to even understand the statement it doesn't however follow that the idea is then what we can call or refer to as nothing. All this though is too deep lol but as for ART which i think was ur main question I really don't know lol.