How to use Metasploit to exploit unpatched web applications

Question

I am learning penetration testing and want to understand how Metasploit can be used to exploit vulnerable web applications. My key questions are:

• How to identify suitable exploits in Metasploit’s database.
• How to configure and launch an exploit against a test environment.
• How to interpret successful exploitation and gain access.

A step-by-step example using Metasploit to exploit a known CVE would be helpful.