Welcome to the NPoco! NPoco is a fork of PetaPoco based on Schotime's branch with a handful of extra features.

public class User 
{
    public int UserId { get;set; }
    public string Email { get;set; }
}

IDatabase db = new Database("connStringName");
List<User> users = db.Fetch<User>("select userId, email from users");

This works by mapping the column names to the property names on the User object. This is a case-insensitive match.
There is no mapping setup needed for this (query only) scenario.

Checkout the Wiki for more documentation.