1. If you have not already, you will need to download a 32-bit or 64-bit Windows 8 or 8.1 ISO file, and save it to your desktop.

2. If you have not already, download and install the Windows 7 USB/DVD Download Tool.

(At site)

3. Run the Windows 7 USB/DVD Download Tool, and click/tap on the Browse button. (see screenshot below)

 

4. Select the downloaded ISO file (step 1), and click/tap on Open. (see screenshot below)

 

5. Click/tap on Next, and do either step 6 or 7 below. (see screenshot below)