Adding Member Login to Existing Website

I have a few days to implement a login system for our existing website.

The existing website is built on ASP.NET using the .Net Framework 4.6.

I have added Forms Authentication. I can't seem to get the OWIN to work unless I convert the site to MVC first.

I have found a couple of good tutorials from Microsoft:

https://msdn.microsoft.com/en-us/library/ms998317.aspx
https://msdn.microsoft.com/en-us/library/ms998347.aspx

However, both of them are for ASP.NET 2.0. I don't know what version I'm at now, but there doesn't seem to be a way for me to create or manage my users becauseVisual Studio 2015 does not have a ASP.NET Configuration section.

It seems like all of the examples I find are either ASP.NET 2.0 orASP.NET MVC. Were there no other options?

How do I configure my users?

For extra help, after I get this database working, is there a way new visitors can login using Facebook and have me go into the database afterwards to associate aFacebook record with one of my SQL records? We know who our members are, and we would like to make it easy for these old veterans to log in. If I can match their email address from Facebook with an email address from our roster (SQL data), I would like to join the two records.