You must keep the job for which the H-1B visa application was made, and earn a regular paycheck from that job.
Speak with your employer about the company's continuing-education policies. Your employer may not allow H-1B workers to take a formal school course. Ask about any financial aid, in the form of grants or loans, they might extend for work-related courses.
Consider your work schedule. If you work daytime hours, consider the possibility you may have to work overtime, nights or weekends. This might interfere with any classes you might take, or with your ability to complete homework assignments.
Get a copy of the class schedule of nearby vocational or technical schools, colleges and universities. Find out what the application requirements are. The school may not accept students who hold an H-1B visa. Normally, those arriving in the United States to study must have an F1 visa. You can't have both, and you can't change your status from one to the other without leaving the country and going through the visa application process again.
You can apply for a "green card" (permanent resident card) while in the United States on an H-1B, if your employer agrees to sponsor your application. If successful, your permanent resident card grants you status as a "lawful permanent resident," and allows you to work, study and travel without restriction.