Designing a member area on my site

If you never heard of WordPress, you can have an overview at the Codex in Getting Started with WordPress and explore the topics as the need arrives.

G.M’s linked Answer has very nice information for your use-case, and sample code with advanced techniques. Worth bookmarking.

To get really started, learn how to make a Child Theme. Understand the Post Types concept. And get a couple of content management plugins like Custom Content Type Manager (to deal with Custom Post Types and Custom Fields) and Advanced Custom Fields (this one has many features not present in CCTM *). Backup and security plugins are also a must.

* Like creating fields in the User’s profile page and making connections with other post types -case you want to link users and a custom post type.

Plugin or products recommendations are off-topic in this site, as it is a matter of opinion and many plugins come and go. So, it’s up to you to research the ones that match your needs. As general rule, check the plugin history, support forums, documentation, frequency of updates, tutorials and reviews.