Take a free online COBOL course, which can help you learn COBOL step by step, building on the knowledge you learn during the program. You don't have to pay for this---a free course can put you on the right track. For example, the Department of Computer Science and Information Systems at the University of Limerick offers an online version of its COBOL programming course. To complete it, simply read through each of the lessons, then ask yourself the self-assessment questions. The course includes animations to aid your understanding.
Interact with other COBOL programmers in forums. Sometimes you just get stuck on a piece of code and need a pair of fresh eyeballs. By talking with others on forums that specifically deal with COBOL, such as the one at COBUG, you can get the help that you need.
Take an online certification course. If you'd like a professional certification to show that you understand COBOL, which looks good on your resume, then you should take a course that results in certification. Through the Institute for Data Center Professionals, IBM and Marist College have teamed up to offer professional certification. You can take the courses online and receive certification upon successful completion. The COBOL programming course is only offered in the fall and costs $2,000. It consists of three classes, which you can complete in one semester.