To put it simply. . .
That's because PNP's are opposite to NPN's. I think that's what's confusing you. If you look at the tip42 datasheet, all of the voltages and currents are NEGATIVE.
It's probably best to get used to how NPN's work before you go onto PNP's, that will be less confusing.
If you really want to try this circuit, don't worry about -5v and 0v if you don't have a negative supply, just use +5v instead of 0v and 0v instead of -5v (ie. reverse the polarity)