Booting from USB

I have an Alienware 17 R4. I have no problems with it.

I have created a windows 10 Recovery USB drive (there is no optical media drive)  and would like to test this.

How do I boot using this.

I have a copy of Acronis backup and recovery software and would like to use this to recover in case something bad happens (i.e. hardware failure, ransomware attack etc.)

I can create the media.

I can press Esc while booting and select F12 to get to the boot menu but nothing I try seems to enable one to boot from my USB drive.

Are there any step by step directions I can use to accomplish this.