We prepared tutorials explaining how to replace the inner tube of a rear wheel (tutorial, video model 2019) and a front wheel (tutorial) in case of a puncture. You can also go to one of your local dealers to get your bike repaired. Here are the ones we do recommend.
To avoid punctures, we recommend to check your tire pressure and inflate them up to 4 bars (model 2019) or 5 bars (model 2018).
Please also bear in mind that riding a Cowboy bike is different than a normal bike. Your Cowboy bike has a motor mounted at the rear side, which means curbs and boardwalks have to be approached with care.
We recommend standing on the pedals when going over these bumps. By doing so, you will place more weight over the front wheel, and the general weight will be better distributed over the bike.