At startup keep pressing F2 to enter setup then navigate to the booting devices page.
You need to move USB devices so that it comes before your hard drive in the booting order. When exiting BIOS make sure to save the changes.

iirc you navigate using the up and down arrow keys but there should be some instructions on how to change the boot order on the actual page itself.

thanks for the information.  So this system can boot from the USB drive, right?  Since I do not have the system is front of me, how do you navigate to the boot priority screen?  Can a non-technical person do this.  My sister is not very computer technical.