To strictly answer the question: The HOA is a legal entity and you would sue it just like you would any other entity. You can check SDAT for the resident agent, who would be the one served with the lawsuit. At the end of the day though, you have to ask yourself whether or not it's worth the time and expense, and what you hope to get as a result of the lawsuit.
Start with contacting the Consumer Protection Division of the Maryland Attorney General's Office. From your brief description they can likely assist you with at least part of your complaint. I'm including a link to their brochure on homeowners association issues. They will also be able to tell you if any of your concerns/issues are outside their authority to assist and can likely refer you to a Maryland attorney with expertise in homeowners association law if some type of lawsuit really is necessary.