Image Writer is free software to create bootable USB sticks on Windows. If you have any ISO file, Image Writer can write that image to your USB stick. It has a minimalistic interface that is extremely easy to understand. Just select your ISO file, select the drive of your USB drive, and click on “Write” button. Image Writer will immediately start writing the ISO file to your USB drive.
If you are trying to burn some OS on your USB, and do not have ISO for that, you can use Unetbootin that will download the ISO, as well as burn ISO to your USB drive. You can use it with USB drive, SD cards, and other memory cards, and it especially useful for creating “Live USB Drives”