It's best to melt your chocolate over a low heat to avoid burning. The easiest way to do this is with the Bain-Marie set up. This technique is used when cooking delicate dishes and is designed to avoid any curdling or burning.
To set this up, all you need to do is place a heat proof bowl filled with your chocolate over a saucepan of simmering water, the steam from the water will create an even, gentle heat that will melt your chocolate. Make sure your heatproof bowl doesn’t touch the base of your saucepan, also avoid overfilling your saucepan with water.