To get your very own custom URL for your. YouTube channel is actually very, very simple.
The first thing you'll need to do is log in to your business YouTube channel. Please don't use your personal, use the one that you're using for your business. In this case I have it here for a client. On the right hand side, look for channel tips. In this case, the first option is get a new custom URL.
Click on the button and then click 'get yours now'. YouTube will automatically determine what that URL is for you, and it's going to be for both your YouTube channel and your Google+ account, if they're linked together. All you need to do is click the 'I agree', and then change the URL and confirm your choice. Now you have a custom URL for your YouTube channel.