Using LM2575 switching regulator
LM2575 is a switching regulator. See the datasheet, p. 2, figure "Typical Application (Fixed Output Voltage Versions)" for it's typical wiring.

If you only need to step down from 9V to 5V, and don't need high efficiency. You may choose linear regulator. With it you don't need to worry the switching noise with switching regulators.

You should use bypass capacitors to make your power rail more quiet. Generally, the regulator's datasheet will give you the typical application circuits, like this LM7805, p. 18. If you don't have so many capacitors with different values, you can parallel small capacitors to get a bigger one, such as if you have many 100nF capacitors, you can parallel ten to get 1uF.