You can do it the easy way or the hard way.
Hard way: Melt down your solution, and use electrolysis as Alberto_Kravina said
Easy way: Make a brine solution (30 grams NaCl in 100 mL of water). Make a circuit with two 9V batteries, with pencils (or use the grafite from a bicycle-dynamo) as anode and catode. Let the circuit run through a small light bulb.
Downside with the last method: You wont get sodium-metal, but a lot of hydrogen gas, chlorine gas and a basic water solution (as the sodium reacts with the water). As the time goes by, you will get a stinky green soup, where the grafite also starts to decompose. But until that time, you have created a lot of hydrogengas.
Dont breath in the chlorine-gas, since it is extremely poisonous.