To access cascade particle editor, you need to create a Particle System in Content Browser by right-clicking on the Content Browser and selecting Particle System. When you select it, a new Particle System will be created and it prompts you to rename it. Give it a name and double-click on it to open cascade particle editor.
Once you open it you will see a window like this:
Cascade particle editor consists of five primary areas and they are:
Toolbar: This contains visualization and navigation tools
Viewport: This shows the current particle system
Details: This lets you edit the current particle system, emitter, or modules
Emitters: These are the actual particle emitters and contain modules that are associated with the emitter
Curve Editor: This is the editor that lets you modify properties in either relative or absolute time