My best advice is to play with the program
I can't select my image to edit it what am I doing wrong?
To edit an image you will need to make sure it is a layer and not the base object:
Click on the picture
Choose cut
And paste it either back onto the original image or into a new document you will then be able to select the object for editing
How do I erase a background?
select your item
on the left of the screen is a toolbar - there looks like what appears to be an eraser - when you click on its arrow - it says object magic eraser
if you choose this - it erases all of one color - so if your background is white - boom done!
you can choose different degrees of matching - so you can get all shades of blue - but be careful if it matches something in what you want - it will be erased
The easiest way to learn photoimpact is to take an image and just start trying all the different effects