what is a sceenshot?, how do you put it in? Options

[demomode]

im new, never use this stuff, now one day i was like oh well i'll make a layout and try to send it in, i did already, but i have no clue that the screenshot was, i read all that advice junk, they only say it's necessary, i can make the screenshot, but what am i doing wrong... i had to link something to show how the image looked like instead, screenshots look better =\ if anyone can give advice, as in not some few random words only experts would understand, but seriously like steps, then i'll e really happy =]