Can t reinstall mac

If you erased the whole drive for Windows, then you also destroyed the local recovery partition. You will either need access to another Mac from 2008 to 2015 in order to create a bootable macOS 10.11 El Capitan USB installer using the instructions in this Apple article (read the instructions very carefully as there are multiple steps to extract the installer from the downloaded .dmg before you can use the Terminal app):

How to create a bootable installer for macOS - Apple Support

If you don't have access to one of these Macs, then you will need to reinstall macOS 10.6 Snow Leopard from DVD. However, you need to be careful since some 2009 Macs shipped with macOS 10.6 which means that Mac would need the original gray DVD which shipped with the laptop from the factory (the gray DVD will only work with a single model Mac). If the laptop originally shipped from the factory with macOS 10.5 Leopard, then you will need to use the retail version of the macOS 10.6 Snow Leopard DVD.

I'm sure you realize now that you should always have a plan in place on how to reinstall the OS before completely wiping an OS from a computer.

Apple never released macOS on a USB stick and Apple has no official instructions for creating a bootable macOS 10.6 USB installer. You still need the proper DVD for your laptop. If for some reason the optical drive on your laptop is non-functional, then you will still need a working optical drive even if you wanted to attempt to create a bootable macOS 10.6 USB installer from the DVD. If you have access to another Mac with a working optical drive, then you may be able to find some very old instructions online from Apple fan sites for making a bootable 10.6 USB installer from the original DVD.

Do not use any OS you download from the Internet that does not originate directly from an Apple server because you have no idea what nasty surprises may be in it (such as capturing your personal data or acquiring your passwords), or if the OS is even complete.

If you do have access to another Mac from 2008 to 2015, then creating a bootable macOS 10.11 USB installer is your better option.