How to download dependencies from behind a proxy

I have been trying several different tutorials for building web APIs and web applications using clojure, but I keep getting the same errors. Due to the bugs in the bugs, it looks like the problem is with my network, but I'm having trouble figuring out the exact problem and figuring out how to resolve it.

This is the error message I get every time I try to run: lein run

Could not find artifact org.clojure: clojure: jar: 1.2.0-beta1 in center ( https://repo1.maven.org/maven2/ )

Could not find artifact org.clojure: clojure: jar: 1.2.0-beta1 in clojars ( https://clojars.org/repo/ )

Could not find artifact org.clojure: clojure -contrib: jar: 1.2.0-beta1 in central (SAME AS FIRST LINK)

Could not find artifact org.clojure: clojure -contrib: jar: 1.2.0-beta1 in clojars (ALSO AS SECOND LINK)

This could be due to a typo in: dependencies or network issues. If you are behind a proxy server try setting the "http_proxy" environment variable.

If anyone knows how to resolve this please let me know. Thank!