I cant access into Facebook page

Good day I am having problem into the Facebook page. When i click enter after the web add, www.facebook.com been keyed in, there is this msg prompt out as below:- Unable to connect Firefox can't establish a connection to the server at www.facebook.com. * The site could be temporarily unavailable or too busy. Try again in a few moments. * If you are unable to load any pages, check your computer's network connection. * If your computer or network is protected by a firewall or proxy, make sure that Firefox is permitted to access the Web. Kindly help. Thanks.