Connection refused message means that JMeter isn't able to connect the target website. If you can open the URL in browser, most likely you're sitting behind the corporate firewall and hence you'll need to perform some extra configuration to "tell" JMeter your proxy server details.
There are at least 3 ways of setting the proxy parameters for JMeter:
Command line (via command-line arguments to JMeter script) like:
jmeter -H your_proxy_server_IP_or_hostname -P your_proxy_server_port ....
Using system.properties file. Add the next lines to the system.properties file:
http.proxyHost=your_proxy_server_IP_or_hostname
https.proxyHost=your_proxy_server_IP_or_hostname
http.proxyPort=your_proxy_server_port
https.proxyPort=your_proxy_server_port
Basically the same as point 2, but aforementioned system properties are passed via -D command-line arguments:
jmeter -Dhttp.proxyHost=your_proxy_server_IP_or_hostname -Dhttp.proxyPort=your_proxy_server_port ....
References: