The Service Menu contains all possible jobs that can be done through your Work Bay without clicking on your random friend visitors' cars, it can be accessed by simply clicking on any unnocupied Work Bay. Considering you have a free Worker, you can start a job by clicking the red "Start" button from the Service Menu. You can cancel a running Job by clicking the red "Stop" button but you will lose the money used for the Job Cost. Observe carefully, as all jobs have Mastery indicated by the stars above their logo, and become fully mastered when they reach 5 stars. Improving Job Mastery won't give players increased payment, but will get more XP instead. Reaching each level of Mastery will give you one-time reward as described on each individual Services Pages. Try to compare the Services to find the one that will benefit you the most and suits you best.
Notice, some of the jobs are initially locked, you must reach certain Level to unlock them. Once a Job is finished, you must click on the Coin indicator on the Work Bay to obtain both of your payment and XP. Your customers will wait for you to collect the payment, their waiting time is equal to the Job Duration. However, if you don't gather your payment and XP until their waiting time expired, customers will leave, so not only you won't get any payments but also losing money because of the Job Cost.