Second hand MacBook but can't install

Hi everyone,

I'm an IT student who has worked with Windows for all his life and I want to know more about apple and osx.

So I bought a second hand macbook, but it still has OS x lion installed, or well it did untill the seller wiped the drive.

Now when I try to install OS x lion fresh it says the article is unavailable.

I do not have a spare Apple product to use and I would like to end up with El Capitan, what is my best course of action?

It's a medio 2008 MacBook 15"