A '78L05 is not a transistor; it is a three-legged linear regulator. It makes 5V; not 15. You can buy a '78L15 or a '7815 which will make 15V.
To get the -15V for a dual (split) supply, you will need to get a '79L15 or '7915, and you will need a second set of components in the blue box,
Since you need a center tapped transformer, you cannot use a single output DC wall wart. If you can get a 20 to 25VAC wall wart, write back, and I will show you how to use that to get a split supply.
This what the dual/split supply will look like: Do not use 1N4001s; use 1N4004 to 1N4007s, instead.
**broken link removed**