Welcome to the forums!
Currently, there is no way to directly update your Galaxy Note 2 to Android 4.3 using Samsung stock software. Some rumors have held that the Note 3 will be released with 4.3 and then rolled out to Note 2, S3, etc, but those are just rumors to this point.
However, if you want to search this site, there will be many step by step instructions to root your phone and install custom software, including 4.3 software when CM makes it available.
Hope that helps!
