The first step when a client hires you to provide a service for them is to add a new Job in Tap Inspect.
If you have someone doing your scheduling or setting up new jobs for you, the web account may be the easiest since it can be done from any modern web browser. If you spend most of your time in the field, using the mobile app works just as well.
This video covers scheduling a new job in the mobile app. The web account process is almost identical. Choose the method that works best for you.