I'm not very experienced but I have built a couple of simple websites that used MySQL. If you don't know that it is, it is basically a system that allows you to store information on a database, from which you can access and retrieve information. You start by creating tables that contain different columns with different information about it's entries, for example, a table called "Users" may contain the columns "ID, Username, Age, Email" etc. which are then assigned to each entry. It's also important that you know you must use a different programming language in order to access this data and display it on your website, for example PHP, which requires a bit more time to learn than MySQL. MySQL is really not that hard to learn the basics, but the deep concepts are harder to learn, but if you're planning to build a not very sophisticated website, you will be fine.
Here's a little SQL query just so you can see how it works. and how accessible it is:
SELECT Username FROM Users WHERE Age=19
This query will retrieve all the usernames from the table "Users" where the age equals to 19.