Create Intellij IDEA plugin. Store plugin settings

I am new at IDEA plugin development and I have a plugin that I need to support. Now there are some settings for this plugin. GarageBand I want to create settings that will be stored at the project level, but I don't know how to do this.

I have created the UI part:

class SettingsPanel implements Configurable

but I don't understand how I can store some information on project level and use this information in my action for example. I want to show project folders structure at my settings panel and save selected folder name.