help with eraser

[Sir Richard James, McDonald]

I need some directions on how to use the eraser.  When I click on the 
eraser and then go to the image, and try to erase the background, it 
turns the whole image to pink and the eraser does not work, is there a 
tutorial on using the eraser???  I have been using Photoshop to change 
the backgrounds and I am trying to not use windows.    Thanks Richard

-- 
Have a great day -