Overlapping photos??

i saw this photo on an internet forum, with a man in his living room. but, there were 5 or 6 of the same man. all in the same room, but in different positions, like asleep, eating etc. is there a way to do this? does it involve overlapping photographs? i have a tripod and a digital camera, but no photo software. i cannot afford to buy any new software to do this with. HELP!!