Nginix proxy caching - how to check if it is working?

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http://serverfault.com – I have set up my nginx.conf file to use proxy caching from tutorials I have found online. However, I am trying to figure out how to check if it is actually working. I've read somewhere that adding add_header X-Cache-Status $upstream_cache_status; to the config file in the server section should add a caching header to a response that will show if it was from cache (has values of either a HIT, MISS or EXPIRED). However, I'm wondering WHERE I can actually view this header(and its value) as well as if this is the right way/if there is another way. I'm very new to web in general so sorry if this is (HowTos)