I just got this computer from a friend and I get nothing but a black screen. Do I need a specific keyboard? Is there a secret to getting the monitor to come on?
I would make sure it is connected fully / all the wires are firmly in, and if the monitor has more than one input (say VGA and DVI), you have selected the correct one (If it doesn't have an auto select feature).
Failing this, it is possible it was damaged in transit, or even the graphics card inside the computer has become damaged.
I think the first part is more likely to of happened, but you can't rule out the second - but without seeing the machine or having a lot more information, it is impossible to say for sure.