They get the money by printing it. It's all on paper. And then we go deeper into national debt which rests on the backs of taxpayers
Shiloh,
Fed money supply is pure inflation. There is no national debt implication there. If anything, the national debt comes down in real terms since the money is debased. That is why exchange rate of $ falls.
Think of national debt as your mortgage or credit card debt. Now think of Fed's money supply as a color laser printer in your bedroom printing counterfeit money. You won't increase your debt by printing your own money. The only difference here is what Fed is doing is legal while if you do it you quickly end up in jail!