Okay, so we start with your base - I've cut and resized a picture of Viggo Mortensen from one of the Flaunt photo shoot images for this particular tutorial, so that's what we'll be working with:


The first thing you'll want to do is promote your background to a raster layer, on your layer palette - right click, a menu should pop up.  Select "Promote to layer".  IMAGE. NEXT IMAGE.
Next, select your lasso tool. IMAGE.
You'll want to use these settings on your lasso tool: IMAGE.
Basically, you pick a starting point, anywhere you like, close to his body - I always choose the head and work my way down.  The way I have my lasso tool settings, it's pretty much point to point, so you right click once initially, that will be your starting point, and then start dragging the lasso selection down, I actually right click a lot, so that you can get as much out of the initial background deletion as possible. You outline the body by right clicking all the way around it.  When you're almost done, it should look something like this: IMAGE.
When you've gone all the way around and reached your starting point, double click, and it will connect to your starting point, and basically float the selection, looking like this: IMAGE.
Next, you go to the top of your PSP 7 menu, where it says SELECTIONS. Go to SELECTIONS: INVERT.  IMAGE.
It should now look like this. IMAGE.
Hit your delete key on your keyboard.  Now you should have a transparent background. IMAGE.
The next thing I want to do is clean up my image a bit more, so I zoom in once or twice, so I can see any of the tinier details I might have missed, close to the body.  Go to the top of your PSP 7 again, IMAGE: ZOOM IN BY 1. If that's not close enough for you, zoom in again. IMAGE.
I go back to my lasso tool. I've moved my tools toolbar to the top of PSP, but if you haven't done that, yours will still be on the left hand side. IMAGE.
And then go back to point by point, right clicking, until you get all the bits and pieces off of the image that you can. It will look something like this when you're done: IMAGE.
Next, we're going to go to EDIT: COPY. IMAGE.
Then, you minimize the image of Viggo, and go to whatever texture you want to use to put your person on.  For the purposes of this tutorial, I've picked one by dearest.  When you have that open, go to the top of your PSP 7 again, EDIT: PASTE AS NEW LAYER. IMAGE.
That's it!  You'll probably want to add effects, or whatever you like, to make it look how you want, or move it around, add different effects. This is how mine looked. IMAGE.
And then I played about with it a bit, repositioned my image, flipped it, added text, and came up with this:


That's it!  I hope this explains things clearly - please post any questions or comments you may have.