Zagdex I think Jepps call it !
The big black names are for orientating you to the general area, the really clever bit is the way Jepps get you to individual airports.
If you look at the airport listing each airport has a code that looks like this p2d or p3d. These codes help you to quickly locate an airport.
Let us say the airport has a code of p2b, to find it on the chart open the chart so the page numbers are at the top, now open the chart to page 2 (that is the p2 bit). Now you will find that the page is decided by the folds into four parts, the top one on the left is "A" top right "B" bottom left "C" and bottom right "D" so you will find the airport p2b on page two in the top right quarter of the page.
I hope this helps !