Unplug your Behringer power hacksaw machine from the electrical outlet.
Go to one of the ends of the old hacksaw blade and, with a hexagonal tool, remove the damper(s) that holds it in place. There will be either one or two dampers holding the blade, depending on the model of hacksaw you have. Remove the damper(s) from the other side of the blade as well.
With leather-gloved hands, remove the old blade and put it to the side. Be careful and take your time with this so you don't injure yourself.
Grab your new blade and slide one end into the machine until the lengthened end slides in perfectly into the blade notch on the machine.
Center the blade on the damper(s) and, with the hexagonal tool, secure the damper(s) in place until snug. Do the same for the other end of the blade.
Discard your old blade in the metal recycling bin. Power hacksaw blades are not sharpened after they go dull.
Plug your Behringer machine back in and turn it on to see if it moves properly. If not, unplug it, realign the blade and tighten.