How do giveaways on here work?

Hi, im new here on biasroom and i saw that they are doing giveaways every day. I find it very exciting but im not sure if im joining correctly. I just click on the europe one (as im from Europe) and submit. Do i need to do something else? I also see that they have prices listed on that photocard that they are giving away. (You see the price if you click on the pc for more information) Does that mean you still have to pay for it? And last question if you win do you need to pay for any shipping or not? Thank you!