Open the picture, and View/Zoom In, so you have the image big enough to easily handle it, meaning go around it with your mouse. From Tool Palette select the lasso tool(it's with the selection and Magic Wand), and from Selection Type, select Point to Point. Then just start clicking around the image you want cut off, going as close to outline as possible (that's why it's good to have the image Zoomed IN). When you ariive back to the starting point, just click twice and the selection will show up around the image. Now either Cut and Paste as new image, or Selections/Invert and Clear, and you will have just the image without background.
If the background is one colour or nearly one colous, you can use the Magic wand to select areas to Clear, holding shift down while click with Magic Wand allows multiple selections. If the background colour has different shades of one colour, you can try to increase the Magic Wand's Tolerance #, usually 25-35 is good enough for normal work.
Ask if you didn't understand something, I'll be happy to help more. Happy Scr#%ing around!