For writing images to USB drives on Linux, we recommend `mkusb <https://help.ubuntu.com/community/mkusb>`_ a tool developed by a Lubuntu team member, or the usb creator shipped with lubuntu `Startup Disk Creator <https://manual.lubuntu.me/3/3.1/3.1.4/startup-disk-creator.html>`_ .
With your media inserted, reboot your computer. Depending on your hardware configuration, it may boot into the image right away, or you might need to press a key at startup for boot options. This varies but looking for documentation specific to your hardware will likely provide the answer.