When you downloaded the Materials for a new Tutorial

there is very often a Gradient for you to use

So in the Materials Folder you downloaded for the Tutorial Right click the gradient file and copy

I like to leave a copy in the folder

Go to where you have your My PSP Files folder in that folder is another

folder called Gradients

Back in  your PSP program click the Materials Palette

Click on Gradient click the drop down arrow

you will then see all your Gradients scroll through them  until you find 

the one you want. Then click the Gradient 

You get this

In the Tutorial you are doing you will have been given instructions on the settings to use in here 

click ok when you have set it up

You can now Flood fill your image with your Gradient 

Hope this works for you.

Have Fun