It's not automatic - or shouldn't be used that way. Something like this:
Remember that it can work stand-alone (how I do it), or as a Photoshop plugin (I think)
It uses artificial intelligence, so the results depend on how/what it samples.

1. Load your image

2. Use  "Device Noise Profile" tab. Use (drop list - "..Auto with calibration target"). It will do some processing. You can move the "target" square around and re-process (use the big "Auto Profile button, not it's drop list). On the right, I set the noise profile to RGB as the "working color space" - this will cause a reprocess. You now have a "Rough Noise Profile" to work with.

3. Fine tune it: Go to "Noise Filter Settings" tab and click on "Preview". Zoom your image larger if you like. You get a square where the final result will show. Move it around to check different parts of the image, while you adjust the right panel controls for "Noise Reduction Amounts. Set all levers to zero, then start with the high frequency (smallest "grains") noise and adjust up from zero until you get rid of the grain without blurring the image (typically 50% to 75%).

If you still see larger "grain" do the same for the mid frequency and maybe the low frequency. Don't do any more than necessary, if you want to keep a nice sharp image.

If most of your noise is in just one color channel, you can control that as well.

4. When you're happy, save your image with the "Output Image" tab.

As usual, a detailed explanation makes it sound harder than it actually is - once you've done a few images, it becomes very quick and easy. 

Of course, they have a help system. so RTFM.