a couple questions

Question

i'm really new to C# so please bear with me. 1. how can i test for input when the program isn't focused. such as if it is minimized and i have IE or firefox open, then i hit a key combination and have the window pop back up. how would i have it detect the keys? 2. how can i make programs that dont have a window? i saw this guy in my class make a program that turned the screen black, and had a little flashlight looking circle where the cursor was that showed what was behind the black. i was wondering how he did it, he used VB to make his so i don't know if its a VB only thing or not. 3. the same guy made this browser(i think he made it) called DNS browser, he said it uses IP adresses or something to get to the site. but he's able to use that browser to get past whatever security settings our instructors put up so we wouldn't be able to access the internet. he also had the function in question one, if you hit shift and the + sign on the keypad it would show up, if you hit shift and minus, the opacity would go down till 0% then disspear from the taskbar, then show up again with shift+. i just wanna know because that stuff seems cool, and i don't know what i'd look for to find out how to do that kind of stuf.