How to update iPC 10.5.6 to 10.5.7? Please help me

[aljonama]

Hi,
Can anybody help me please. If there a Step by Step guide to Update my amd IPC 10.5.6 to 10.5.7.
I'M SO HELPLESS about Updates...
... For exsample... What is seatbelt.kext.

If It's Possible me by Puttabong can help in German...
or Anybody else

So, Thanks so much
Aljonama