Yes, this is incorrect. Host files are designed to map a single host or a list of hosts to a single IP address. Instead, you've attempted to map a host to a host.
Assuming www.another.com and www.somesite.com do point to the same IP address, you could try the following.
1 - Ping the address you can resolve, which is www.another.com.
2 - Assuming the IP is 188.8.131.52, copy it into the host file, enter a space, then enter the domain you wish to map.
3 - On Windows, you may need to flush your browser cache. Open a command prompt and type:
4 - You may still need to restart your browser. On Mac and Unix-based systems, the changes should be immediate.
Note that, depending on how the site is blocked, you may need to use other methods to get through. If it's blocked by your ISP and not DNS, then you'll likely need to look for an Anonymous proxy in order to fetch the content from a proxy in another country. You can find some proxies here, as well as on Google. Good luck!
Note: You can add more than one host to a single IP by spacing out the addresses:
184.108.40.206 my.domain.com www.somewhere-else.com anotheraddress.net