You need to have developer access to install or create new databases. If you don't have developer access ask the project owner to give it to you.
Login the project and click the Developer button from the left menu.
You have two options to add a database to the project. You can start from scratch or install a pre-made database. These pre-made databases can be tweaked in any form or shape (see article).
In this example we are going to click the Add database button to create a new database.
You need to set-up your database with the following starting data:
(1) Add a name for your database (blog, news, ...)
(2) Fill in the main category for your database. You will be able to add multiple categories in a next step.
(3) Add at least one property filter. The default one is published. Check the status for the default value when a new entry is added. You will be able to add more filters later.
(4) Add at least one order field. These fields are used to order the data in a list. You have 3 types of order fields: text, number or date. You can add more order fields later if you want. But you need at least one. The default order field is date.
Click add Database to create your database.