Can someone please "translate" this tutorial?

[johnricard]

I'm attempting to follow a Photoshop tutorial, but I'm having trouble creating the layer mask. I can create it, but I don't understand how to make the paint brush "erase" the layer below it. I don't see the little White and Black boxes that appear in photoshop to make the layer mask either visible or not visible.  If someone could rewrite the tutorial below so that it works in Affinity Photo, that would be super appreciated. 

 

I just need these 4 steps rewritten.  I have also posted the original source article link:

 

Create A New Layer. Type Ctrl-J (Command-J) or flatten all the layers into a new layer using Ctrl-Alt-Shift-E(Command-Option-Shift-E).

Add Median Blur. Click Filter > Blur > Median. Then select a Radius of 15 - 30 Pixels depending on the amount of dirt and grime on the background. In the preview window, make sure the dirt completely vanishes, but the shadows retain detail.

Create A Layer Mask. Click the Layer Mask button and then tap Ctrl-I (Command-I) to invert the mask.

Paint On The Median Blur. With a decent size white brush paint on the Median blur over the problem areas and watch the dirt disappear! Be careful of any edges, I recommend using a small brush to cover the fine details around shoes or props.

 

https://fstoppers.com/commercial/save-yourself-hours-most-effective-way-clean-backgrounds-photoshop-32144

 

Thank you in advance.

[Trinity]

Hello, I think what you are referring to can be found on the top right hand side of the screen under the tab colour. You should see the histogram, colour, swatches and brushes tabs. There you can change from black to white by pressing the shortcut x. That will give you the ability to erase the dirt on your image using the white paint, or if you go to far and make a mistake to rectify it by using the black paint. Also make sure you have selected a pixel layer

Hope that makes sense. good luck...

[Madame]

Create a new layer is the same in Affinity and Photoshop.

Ctrl or Cmd J is also the same. It duplicates the layer or selection you have selected.

Ctrl-Alt-Shift-E(Command-Option-Shift-E) is also the same. You can also right click in the layers panel and choose merge visible.

To add the blur, go: Layer>new live filter>median blur. It comes with it's own mask so no need for adding mask.

To invert the mask; Go Layer>invert. (The mask has to be selected, not the layer.)
To paint in/reveal the blur, pick a brush and paint with white on the (inverted) mask (be sure the mask is selected, not the layer).