On this page are links to PDF's that will hopefully get your head around stuff in Photoshop:
7 Mar 2021 - "Watercolour" - see here
7 Mar 2021 - "Black Ink Sketch - Postscript" - see here
28 Feb 2021 - "Black Ink Sketch" - see here
21 Feb 2021 - "Getting Extra from Your Textures" - see here
14 Feb 2021 - "Basic Compositing in Photoshop" - see here