It is a good news for me that AWS provides beginner level service for free. This saved me the cost to buy a VPS. I applied a EC2 virtual machine by following this Youtube tutorial:
Then, I modified the Security Group quick-start-1, which was created by default during the creation of the virtual computer, to enable the port of HTTP.
Finally, I built a sample Go program copied from here:
with the port number changed to 80, the default HTTP port.
It is notable that we need to run it with sudo, because only privileged processes can open and listen to standard ports like 80.
All above can be done in 5 minutes, and we can access our Web server from our browser.