connect desktop to power bi portal

[steveo250k]

I've been all over the web and this community and have not found the answer.

I have several reports created with Power BI desktop.

We have a new Power BI Server.  How do I publish to our server?  I click publish and give it my credentials on our server and it tells me I don't have an account.  It wants to create an account on the MS cloud.  I already have 2 there, but we need these reports on our internal Power BI server.

The reports were created in Desktop Feb 2018.  I downloaded another version of desktop from our server.  It's Oct 2017 and totally mangled our reports.  Even so, It still won't publish to our server.  From the Oct 2017 Desktop I can do a File Open Power BI Report Server and go to our server.  Of course there are no files there to open BECAUSE I CAN'T PUBLISH!

It would seem this is a straight forward function.  How do I do it?