Hey Anthony,
Stratobat has a good idea when changing the opacity of a layer, but that also fades ot the top layer's details.
A very useful feature in itself, but there is a another way that will do the trick.
Since you are using PSP8 and I happen to also, you're in luck. I know my way around the program just a bit.
The feature you're looking for deals with changing the
type of layer you are working with.
When a layer is set to normal (as it is by default), it will, by design, cover up all the details in all layers below it.
Look at my example below:
With my Eastern stripe layer set to normal, it covers the fuse lines which are in a layer below it. (The windows and doors are in layers above the stripe, so they are displayed in full)
Now, in one of those moments where you hear the angles sing and wonder just how many neat tricks other painters know, I set the layer to
multiply.
When you've finished picking your chin off the floor, you've probably noticed that there was an entire list of different layer
types other than normal and multiply. (once you do this yourself in PSP8.) They all have different functionality as you can imagine, but I use normal and multiply about 99% of the time.
Multiply multiplies (for a lack of better terms) all the layer's details thru the layer stack. I can't get into the details in a post like this, but just play with the layer types and you'll begin to appreciate one of the most powerful features in any good paint program.