I am going to be attaching these to wood posts? What type of and what size screws should I use with the brackets?

Kristykay, Use pan‑head #10 × 1" exterior‑rated wood screws to attach the railing brackets to the wood posts. They should be stainless steel or coated to prevent corrosion, especially with pressure‑treated wood. The pan head fits the bracket holes properly and provides a secure, flush connection without splitting the post. - Your Deckorators Team