If you never installed macOS 10.12.6 or 10.13 on this laptop, then you do not have access to Internet Recovery Mode. That means you need to use the OSX 10.6 Snow Leopard DVD that originally shipped with your laptop to reinstall OSX 10.6. Once you install OSX 10.6 and all its later patches, then you can download and install macOS 10.11 or 10.13 using the information in this Apple article which includes links to the various macOS installers as well as optional instructions for creating a bootable USB installer:
https://support.apple.com/en-us/HT201372
If you have access to another Mac that can run macOS 10.11 or 10.13, then you can use that Mac to create a bootable macOS USB installer instead of starting with the OSX 10.6.3 DVD.
FYI, before removing the native OS from any system you should always plan ahead for how you will reinstall the original OS if you ever change your mind. Apple requires you to access the macOS installers using macOS.