Draw 2d thing

[trisman]

Hi , so i did the 2d tutorial , but i was kinda confused , because when u load a 2d image and then u create a rectangle to put a piece of the image inside the rectangle, the tutorial didn't explain how u should locate it on the image. Its hard to explain.
I mean:
core::rect<s32> piraat(25,20,70,100);

Something like this would create the rectangle , but what do the numbers mean? I know it has something to do with the height and width of the rectangle and with the position of the "piece of image" in the image. but wich number stands for what?? :S

Also does anyone have a tip on how i could check, where is what on an image.
F.e if i want to create a rectangle for the imp in the tutorial, how can i get the numbers that i need? I mean guessing is not really efficient

Sorry for my weak grammar , it was a though night yesterday