I can't make a redirect from my own non-www domain to my another www domain

Hi Cpanel community. I work at an E-commerce business and we use your services for server and domain managment. I have no experience dealing with servers but i do have some experience with computers. Right now we are in need to change some redirect's with our domain names but for some reason i could not find an answer for, i'm not being able to redirect our domain name "domain.com" to our other domain "www. I found some solutions online but they did not work either. For example, the redirect code that online forums suggest to be added to the .htaccess file simply does not work. So whenever i edit the .htaccess file, nothings happens. This maybe happening because, as i have read online, the .htaccess is not enable by default in our server configuration. I tried unsuccessfully to find how i could turn this file on, but i havent found the answer. It seems that i should access our servers through a Linux system, or the ms-dos in windows, but i don't know how can i access our servers via prompt. By using the cPanel redirect user interface, nothing happens either. So at this point i'm unable to find the answer. I have readed a lot of information online, and i also have searched this forum before posting this thread, but still i can't found what is the exact problem i'm facing. I would guess that it is the .htaccess file that is not enabled, but any form of solution is highly appreciated. Thanks in advance.