how to do backup please guide me

Hi I have a domain and hosting and i am looking to create 3 blogs backup. now the thing is that when i create 1st blog and start backing up using WP complete backup. when i download full backup after that just to check i format full wp dashboard and try to restore those files to make it sure is it working on it. when full backup load the plugin said to logout in order to complete backup i logut and login in again when i check the blog there was nothing. means my backup files is not working. please guide me what to do?

thanks