A new database is always empty. To create a field, it suffices to name it. The default field type is “Text”.
The field types that are available depend on the driver you use. The default driver is currently the most comprehensive. Field type selection is done through a pull-down menu, which appears when you tap on the right arrow.
On the left-hand side another arrow allows you to access a second pull-down menu. Its use is defined further on in this documentation and in particular the way to change field properties is covered there.