It just depends on how you want to use it. You don’t need to add any code to use it with the free IFTTT service so you could just have Leeo detecting a sound then activate any of your SmartThings-controlled Devices like a siren or a light. That’s pretty straightforward.
If you want to get fancy and have it treated like a smoke alarm and use it with the smart home monitor feature, then you would need to use one of the custom code options I linked to above.
If you haven’t used custom code before, it’s fairly straightforward. Basically you copy the code from the author and paste it into your own account. The following FAQ describes that basic process, but you need to read the exact instructions in the author thread for any code you were going to use because sometimes there are additional things you need to do to make it work.