I need to make some extra money.. if I can get good enough and practice, can I sell my digital photo's? I know about the copyright, that it's your's the second you hit the shutter button. But, how do you go about actually selling a photo??

f you find someone who buys them, of course you can.

the problem is, how you do that, acutally.

like deviantart? you let someone push a "buy" button, you print out your picture and send it to the buyer?
or like "download" and then a paypal-form?

i dont think anyone would do that, so to buy something they could have for free from someone totally unknown.
but you could switch to film and start taking artistic photos and never get tired of asking at gallerys if they want to
expose your pictures or you buy yourself a good camera and work at your local newspaper (not as a photographer but
as a free employee, writing texts about big fruits and stuff) and then get better and better to some day be
an AP/magnum/dpa/reuters/whatever photographer...

hard way to go, in times of digital photography, where everyone can buy a 100$ cam and pretend to be an artist.
some might be but the gross majority is not.

Hey thanks for the info!! I guess for now I should just practice and get better at photography and do some reading..

You might want to have a look at stock photography.
Basically involves selling your images online.

Two strategies;

Micro stock - sell loads (in theory) for 0.50c a picture.

Macro stock - sell few pics, but for $200 a pop.

Both of these, ofcourse having decent images that sell. And don't automatically think you need stunning photographs of sunsets and gorgeous vistas, because business shots sell the best.

Have a look at Shutter stock (micro), and Alamy (macro).