Bazyle, one rule hgere is no question is so simple you shouldn't ask it.
pgk – I use dremels for all sorts of things, but I haven't found one that cuts faster than a hacksaw yet.
Start by drilling two or more holes close enough that they break into each other (use a drill press clamp the metal to the drill table so it doesn't spin).
Unfasten the blade to thread it through.
Turn the work in the vice to keep the frame clear and note that the frame allows the blade to be turned in 90-degree steps.
Hacksaw blades should be set so they cut when pushed away from you, keep the tension nice and high.
Don't force the blade and it will cut straighter and easier, don't keep using it when blunt.
Disregard Bazyle's comment and use one hand on each end of the saw,
Neil