Check your local community or technical college for an adult education course in circuit design. Adult classes are usually short term (one day to a few months), and beginner classes require no previous experience with electronics.
Purchase an introductory text book on circuit design such as "Circuit Design: Know It All" by Darren Ashby et al, "The Circuit Designer's Companion" by Tim Williams, "Introduction to Electronic Circuit Design" by Richard R. Spencer and Mohammed Ghausi or "RF Circuit Design" by Christopher Bowick et al. Select a book with lots of illustrations, blue prints and step-by-step information.
Enroll in a bachelor's program in Electrical and Computer Engineering Technology at a college. Bachelor's degrees usually take four years and involve both general coursework and training on circuits through classes such as "Digital Circuits Applications," "Linear Integrated Circuits," "Electronic Circuits and Devices" and "Linear Circuits Applications." Most bachelor programs require a minimum of a high school diploma or GED.
Join a circuit industry association such as the IEEE Solid State Circuits Society. Industry groups offer local membership chapters, access to conventions and publications, plus a variety of educational opportunities. The IEEE Solid State Circuits Society's educational resources includes tutorials on topics such as "Battery Management for Portable Devices," "Power Gating" and "High-Speed Memory Interfaces."