How to install 1.9.2 (beta) or upgrade 1.9.1 to 1.9.2(beta) under Win10

[naish1]

Unfortunately I am having an issue restoring my backed up mails to a new account (Error: argument of type 'NoneType' is not iterable) and it seems this is a well known error that was addressed by the 1.9.2 beta or a patch.
Unfortunately I am not very deep into programming (yes, the typical dumb windows user) and I am despairing of installing /upgrading to 1.9.2 beta. I couldn't find a howto describing the installation process. Is there anybody here who can explain me (ideally in a way an Windows user understands) what to do to get to the 1.9.2 beta

Thanks for your support!