There are a number of different approaches to take for removing an image from a background. Depends on the image, your time, and your expertise level. Methods you can use include layer masks, the magic wand, the lasso tool, the eraser, the extraction filter, and more - and you might need to use a combination of methods for the best results (again, depends on the image). 

http://www.pixel2life.com/twodded/t_advanced_cutout_techniques_learn_the_professional_method_for_cutting_out_pictures/page1/

http://www.devarticles.com/c/a/Photoshop/Using-Adobe-Photoshop-CS-Part-1/5/

The above are just two of the many tutorials you can find on the web. Google photoshop extraction or photoshop lasso tool and you'll find others. Personally, I start with the extraction filter and then use other tools as needed to clean it up.

HTH,
Don

There is a prior post on this forum that is over a year old but still has links to some great tutorials:

http://www.lunarforums.com/forum/index.php?topic=13327.0

2 of the links are dead, but some of the other links that are still active are just fantastic.  The phong site also has linkpost listing links to other Photoshop tutorials sites.

good-tutorials.com
tutorialsfactory.tk
pixel2life.com
designtutorials.info

they have tutorials all over sites created by teens or college students...such as outspoken-kate.com and on my.stargirl.nu's resources page they link to TONS of tutorials for ps and psp. All the tutorials are for doing different styling and such. And on outspoken-kate.com they have a couple image cutting tutorials along with how to mad psds.

There are many online tutorials are available on the web that you can search easily and start designing. As my point of view Creative Mentor is one of the best place from where you can gain your knowledge through various IT courses training like Adobe Photoshop,Adobe Dreamweaver,Adobe Indesign etc.