what responsibility does our federal reserve bank have as far as our country's monetary policy is concerned?

They are responsible for controlling the supply of money by ensuring the interest rates are set to a level consistent with economic objectives given current economic projections. Lowering interest rates increases the supply of money because people are more likely to borrow and therefore spend more, and vice-versa for a higher interest rate.

The monetary policy in the US is different than most countries though, instead of focusing solely or extensively on inflation, whereas the Federal Reserve provides a monetary policy that focuses on: high employment, sustainable growth, and stable prices.