In the BIOS of your computer, search for an option that mentions about the Boot sequence and make the boot sequence start with A (for the floppy drive), or D for the CD-ROM drive (you may have another drive letter assigned to the CD-ROM drive) or USB flash drive/USB or the option called Legacy USB Support. Save the changes you have made in the BIOS and restart the computer with the floppy disk/CD/DVD/USB disk inside.
Now the computer should boot from the selected floppy disk/USB disk/CD/DVD that contains east-tec DisposeSecure.