OS X could not be installed your computer. No packages eligible for install

I have a MacBook Air2,1 late 2008 and I bought it broken and I fixed it. I ordered a new ssd and a bootable usb. i booted it and when I got to install it to the ssd it says "OS X could not be installed on your computer. No packages eligible for install" I can't get it to install so the ssd. Not quite sure what version of El Capitan it is.