22.04 server install The SSH server question

[DonM]

I JUST installed ubuntu server 22.04 on a dell optiplex with a intell i3 processor it is a small platform 7010 with 16gig of ram and 2 ssd drives, during the install it asked me if I wanted to install a SSH server. I put a X there. IT also wanted my github user name. I put that it and it showed my public key I setup on github.
* that key that I setup on github - THAT key is a public key that I created on a different system. That key must have its pair on the computer I created the key WITH RIGHT ? I am not sure how it works -- how does my new install of ubuntu server use this github key when it was created with a different linux install ( a lubuntu on a windows 10 as a VM)

* In order for me to SSH into my new 22.04 install as a headless server I am going to need to create a public and private key. I need a public key a private key and I need to tell it what kind of certificate I will be using. ? logging into this server with Putty on a windows computer will require some kind of SSH setup ? Right ? I have use commands on the new ubuntu install I am new to these keys but I think they are txt files. like config.d or something like that. Am I in the right ballpark here ? I need to copy the public key and the certificate to a flash drive and put in on my windows machine on the same lan.

* my router allows me to reserve a IP to a mac.. Instructions say to put it ouside the pool but my IP is reserverd and it is set in my router to be reserved to the mac address on my 7010 22.04 server install.

* is the github ssh going to be related to me accessing my server with putty ? o ? I asked this ! THis is a lot to grasp and understand.

I just read "
Please visit (and READ) the OpenVPN HowTo http://openvpn.net/howto prior to asking any questions in here!" OK so I will be doing some more reading.
Anyway I have a server installed tomorrow I am going to try again to install the openvpn remote access server but Im pretty sure I should get the headless access worked out.