This is just a handy way of constructing the start (or "lead") of a news story when you are under deadline pressure, or when the story does not merit greater effort. In this case you get the reader's by telling him or her what they want to know in the fastest and most efficient way possible.
The "Five Ws" are who, what, when, where, why. Memorize them. They will be on a quiz or test. The "H," which is not always included, is for how. (In fact, why is also sometimes omitted from the lead paragraph if it is too complicated, or if it goes without saying.)
To think of it another way, the opening paragraph should tell the reader who did what, when, where, why and, sometimes, how.
It may become clearer if we look at real example from a kind of story we will be covering (games in the Santa Cruz Interscholastic Sports League):
Who? The Cooperative School boys varsity soccer team
What: Defeated Cambridge 11-0
When: Thursday afternoon
Where: The Jaguars' home field
Why? To open the season with a win
How: By outplaying the Cambridge Knight on offense and defense
This might all come together, with some embellishments, as follows:
The Cooperative boys varsity soccer team opened its season in impressive fashion with a decisive 11-0 win over Cambridge in a game played on the Jaguars' field Thursday afternoon. The Jaguars scored early and late, dominating play at both ends of the field.
You can always start a news story with a five W lead, though you may often be able to think of a better way to get the reader's attention. But even when you do you should answer the basic questions signalled by "The Five Ws and an H" by the second paragraph (or at least the third).