In your case it would be better to do a full upgrade to the latest version. To upload the files you can use a ftp client or you can also upload them through the File Manager section in the cp of your host, providing it has one.
Do not forget to make a backup of your database before you upgrade your forum. For just in case things don''t go as planned you can always roll back.
Yes we have File Manager in CPanel, ftp as well ... Should i create a folder before uploading the files?