Oh that's good, cause this one did say it was for the complete novice and takes from the basic steps to more detailed and complex functions of the software, so maybe I will be in luck with a good book and a great and patient tutor.
I hope you will. But working with any computer program is like coding it.You can read tons of books for Assembler or other programming languages.You can go through tons of listings but you still need to practise.
I take it the DPI is the resolution the DPI meaning 'something per inch', all I have on my dropdown box is a Resolution fill-in box indicating pixels/cm. See pic
Click with LMB the new layer title in the window on right side.Then click with RMB on it and choose the Blending Options.In the effect selector click LMB the option exactly below the colour overlay option .It should be Gradient overlay option.Then click with LMB the strip with a gradient colour that will appear when clicking the Gradient overly option.
The new window should be opened.Find in this the colour I have marked in the second pic.Finally you should get the screen like in my first pic in the post.
All is OK. In the Gradient Editor window there is the Load button right? If you click it there will appear other sampleas for uplading more ( adding another set of the gradients).There you should find the colour.
OK. Now you have to modify the gradient range.As you see there are small squares with colours of the GRadient at the bottom edge of the Gradient stripe.Click with LMB on the colour square in the middle of the gradient stripe. The same colour should appear in the bottom left corner of the editor window.( the pic below) Look at the right side of the window please. There is Delete button.Click it and the colour should be removed ( deleted) from the Gradient range.
The same do to the square at the left edge of the Gradient stripe.
OK. Now set these squares as shows the pic below.You can move them with the mouse when clickig any with LMB and keeping pressed. I moved the darkest one to the left side the lightest one to the middle and the last one to the right.
OK. If done click OK button and in the effect selector set these settings like in the second pic.The Angel you can change holding the clue in the circle with pressed LMB.The rest settings like you can see.