Before you learn more about marketing, you should get a basic impression of what marketing is. See What's "Advertising, Marketing, Promotion, Public Relations and Publicity, and Sales?". Basically, you might look at marketing as the wide range of activities involved in making sure that you're continuing to meet the needs of your customers and are getting appropriate value in return. Think about marketing as "inbound" and "outbound" marketing. (In the following, consider "product" to be either a tangible product or a service -- nonprofits often refer to these as "programs".)
Inbound marketing includes researching (with market research methods) to find out:
What specific groups of potential customers/clients (markets) might have which specific needs (nonprofits often already have a very clear community need in mind when starting out with a new program -- however, the emerging practice of nonprofit business development, or earned income development, often starts by researching a broad group of clients to identify new opportunities for programs)
How those needs might be met for each group (or target market), which suggests how a product might be designed to meet the need (nonprofits might think in terms of outcomes, or changes, to accomplish among the groups of clients in order to meet the needs)
How each of the target markets might choose to access the product, etc.
How much the customers/clients might be willing pay and how (pricing analysis)
Who the competitors are (competitor analysis)
How to design and describe the product such that customers/clients will buy from the organization, rather than from its competitors (its unique value proposition)
How the product should be identified -- its personality -- to be most identifiable (its naming and branding)
Outbound marketing includes:
Advertising and promotions (focused on the product)
Public and media relations (focused on the entire organization)...