Blending question!!!

How do you do a blend. I have already looked through the memories. So please do not direct me there because I don't get it. I have tried to blend but it just ain't looking right. So if some could pleae explain it that would be great. I'm using PSP 9 and all the others seem to be either PS or PSP 7 or 8. I know that you can transfer the information into a different verison. Which I have done but I'm still getting confused. Thanks in advance for any help that anyone gives!!!