Ah ha. Yes you would want to use MYSQL if you were an expert and technically oriented, but believe me, it's not worth learning if you're not planning a web application, or very serious about web programming and design. MYSQL is a type of database that permanently stores data that your server can access at anytime, and is exceptionally more efficient and secure than storing this information on a file on the server. So if you were storing account information, each part would be stored in a designated column in a particular table in the database.
Quick answer: You are looking for a content management system or a CMS. Thousands of programmers have come together to solve a recurring problem that most website owners have. That is a need for a fully functioning website that has automated scripts for user account management, theme engines, and easy content control. Try WordPress if you're just starting out, and if you know a bit about web programming and HTML, try Drupal. You'll be impressed with WordPress if you use it properly.
Best of all, WordPress and Drupal are both free.
However, if you're going to design an application or something very unique, you'll need to do some programming. There are many languages you can program in, such as PHP, Javascript, Perl, Python, Ruby, Java, and more.
Trust me, it's not worth the "blood, sweat and tears" of learning to program with MYSQL, unless you are a gifted programmer. I know MYSQL fairly well and can develop with it but I can tell you you're much better off with a CMS. If you must use MYSQL and you don't know it you can hire someone on scriptlance.com to do it for a few hundred dollars.