Where can I find the OS X installer? Everything I've seen says get it from the App Store, but when I search the App Store I get 'nothing found'.

I am trying to build a USB boot stick on one old 15" MacBook Pro for an even older 17" MacBook Pro.

Working mac:
MacBook Pro 15-inch Early 2008
OSX Verison 10.9.5 (13F1911)

Mac with corrupt disk:
MacBook Pro 17-inch April 2006
The latest OS that will run on your machine is Snow Leopard. There is no software download for OS X Snow Leopard. You need to find the install disk, buy a new install disk, or take your laptop to an Apple Store, where they will reinstall the OS for free.