The Free Church of Scotland website can be found at
The Free Church magazine
Castletown Free Church at
Ligonier Ministries- the teaching fellowship of R C Sproul as advertised in The Record https://www.ligonier.org/learn/topics/
The Westminster Confession of Faith summarises what the Free Church believes. It is a summary of reformed teaching, the fruit of the reformation. Baptists have a similar reformed confession, the London Confession. It is almost identical to the Westminster Confession, and was republished by Spurgeon. You can view both here