Paint Shop Pro v7 » Fading
You can fade the horse by choosing Layers (on the tool bars), then choose "Properties". Then reduce the "Opacity", to e.g. 50 %. Here is an example: Open the background pic and the pic you want to fade in to the pic, in psp. I have this pic I want to use as background:

Then I want to fade in these butterflies:

I press Ctrl A (select all), then Ctrl C (copy), then i click on the background pic, and press Ctrl L (paste as new layer). Now the butterflies cover the background pic completly.. Now I click on Layers in the tool line:

and this box opens:

I have added the red circle so you can see what I'm refering too. Choose a lower opacity than 100, like 40, and it will look like the pic below.

This can be done with as many pics you want..