My domian is registered for one year, but, I came to know, that when the domains are registered for longer period, they are trusted more. How can I prolong my domain registeration.
Depending on now have you purchased your domain name, and how have you registered it, you can prolong your domain registration.
If you have done that yourself, you have to contact whoever you purchased your domain from, in other words your Registrar, and make payment for how much longer you want to use your domain. It can be from one month to several years. If you have used someone elses services to do that for you initially, you have to contact them, to do this for you.
You can always check when is your domain registration due to expire if you use WHIOS Lookup tool, where you should enter your domain name, without www prefix.