The first thing to do is install Java. If you're using MacOS, download the Java .dmg installer and install it as you would any application. If you're OS of choice is Windows, download the Windows .msi installer, double-click it, and follow the instructions. For a Ubuntu-based Linux distribution, you can install the necessary package with the command:

Open LibreOffice. If you open a Writer document, you can then click New > Database.

In the first screen of the wizard, leave everything as is and click Next.

In the resulting screen of the wizard, make sure to click the checkbox for Create tables using the table wizard. This will open the wizard, which will walk you through creating the necessary tables for your database. After you've done that, click Finish and you'll be prompted to name your database.

You can select from a wide range of fields (or collection of fields). For example, select Personal from the Category, and then, from the Sample Tables drop-down, you could select CD collection. Once you've done that, you can select whatever fields you want to add by clicking one and then clicking the right-pointing arrow to add it. Keep adding fields until you're happy with the selection. Once you have your fields added, click Next. In the next two screens, you can customize the types and formats and set a primary key. Since this is your first database, you click Next through these two. 

On the final screen of the wizard, give your table a name, select Create a form based on this table, and click Finish.

The database form creator will open with a new wizard. This makes it possible for you to create a form that will allow you to easily enter data into the database. The form creator is simple to use. First, you select the fields you want to add to the form (all of which you added during the database creation). Next, you can set up a subform (which you probably won't need). In the next screen, you can arrange the controls for your form. After that you'll select if the form is used to only enter new data or if it will be used to enter new data and display all previously entered data. You can then add a style to the form and give the form a name. Once you've taken care of that, your form is ready to use for entering data into your database.