Determine what field you would like further instruction and experience in -- this should be different than the area of study on your current business degree.
Confer with your current employer, or with future employers, about opportunities that can be made available by further studies. This will help narrow down your choices.
Search online for schools, companies and organizations that offer both academic programs (usually associate degree programs) and certificates in business-related fields. These can be local universities, certificate companies and even training seminars.
Choose a program that fits your needs -- something that offers record of your successful completion, such as a degree or certificate.
Enroll in and complete the program. Many employers will pay for the program in part, if not in entirety, under contract that you will continue work or accept a new position with your new knowledge.
Add your new supplementation to your resume and include a copy of the diploma or certificate in your portfolio.