Looking for an ASP.Net Core 2.0 custom authentication without Entity Framework

Hi, iam a newbie with ASP.Net Core 2.0. I will have in my Web App a custom authentication. I want use my own SQL Database with my own user table. i want use a simple login process .
When i google i found a sample but for Core 1.0. I read that are many things have changed.
Could anyone help me?
thanks