Not sure why you wouldn't see an option to check for update, but too many people have had severe problems with OTA OS updates for me to advise doing it that way. If you can navigate your computer browser to blackberry.com and download and install the Desktop Software then you are capable of upgrading the OS automatically yourself.
Why do you feel the need to update the OS? Is something not working correctly?
IMHO, if the device is doing what you want and need it to do, it is not broken and, therefore, does not need to be fixed with an OS update. Particularly since you admitted that you were not that computer savvy, maybe you should leave it as it is. Unless, of course. there is a problem.