You can download Windows 7 from the official Microsoft webpage
Windows 7. Take in mind that you will need a working license key which you can purchase from
here. Then you can run the Windows Media Creation Tool to make a bootable USB, you can find it
here.
Once you have installed Windows you should download the Windows 7 drivers for your laptop
here like Philip Corcoran said.
** Make sure to select Windows 7 64-bit in the Operating System dropdown list. **