Courses are generally offered through colleges and universities. Some colleges and universities are now offering certificate programs in human resources. These programs generally require a bachelors degree or relevant experience and can be fairly intense. For example, Penn State's program requires individuals to take six 30-hour courses. They are often non credit programs, so you won't have credits to apply toward a degree if you choose to go for one later.
Many universities offer master's degrees in HR as well as MBAs with HR concentrations.
If you think earning a master's degree will take too long, look at universities that offer intensified programs that allow you to earn your degree in less time. This may require attending class four nights a week or on weekends to cut in half the number of years it would normally take. Some programs may take several years to complete. Look at job postings and help-wanted ads. Ask people who are currently working in those jobs about their education.