Hi Bruce
You have three options
1) Use the Magic wand tool to select the background and then while still selected use Effects> Hue and Saturation to change the color
2) Use the Magic wand tool to select the background and then delete it and replace the background with another
3) depending on the subject, make a selection around the subject using the freehand or edgefinder tools, invert it and then delete or change the color of the background
If you need help with using selection tools then these tutorials should help
http://www.scrapbook-bytes.com/a-tut...ticle_405.html
http://www.scrapbook-bytes.com/a-tut...ticle_159.html
http://www.scrapbook-bytes.com/a-tut...ticle_208.html