How do I access my own server? I started plex accessing through a friends sever.

Now I want to create my own libraries so I downloaded the server paid my $ and all I can access is my friends sever

How do I get to my own account

You don’t have to pay for Plex. Running a Plex server is free. You should read the instructions:

https://support.plex.tv/hc/en-us/categories/200007268-Getting-Started