Brother, first of all answer @suhasa brother question, how you know update available? Connecting with Nokia Suite in PC or something else..|
I have also Nokia C201 Phone. My Phone SW version showing 11.10, and when connect your phone with Nokia PC Suite and connecting internet there is a option for update your phone software, and for your information yes New SW version 11.20 (53mb) available for update.
You can update your phone by connecting your phone with PC via USB cable and open Nokia PC Suite> sign in> the download update. Before update please take backup of all your contacts, messages and apps from your phone to pc (safe place).