To get started you need to create the c:\etc\ssl\uacme directory that
uacme.exe expects to exist.

Then you need to register yourself with Let's Encrypt using

   uacme -v new

to create your production account.  This will create
c:\etc\ssl\uacme\private\key.pem - your account's private key.

At this point, I believe you will not need a staging account.  Staging
accourts are intended for high volume certificate and tools testing and
you should not need any of this.

Once you are registered, create a script to issue your certificate.  I
recommend you edit a copy of

   issue_wwwmbopinion2.cmd

changing the domain list to match the domain set for the certificate you
want to create.  IIRC, the first domain in the list will determine where
uacme writes the cert and key files.  The resulting script will be
something like

uacme -v -h uacme-hook.cmd issue www.pmoylan.org pmoylan.org ...