Moss is a sign that the ground is wet, shady, and has poor drainage.
One option is to purchase a lawn care product that has moss control and follow package directions exactly. You can also try to make it easier for the area to dry by pruning nearby trees and shrubs to improve air circulation and less more sun reach the area. You can improve drainage over time by working compost into the soil. The success of this approach depends on many variables. An alternative is to plant a shade- loving, moisture-loving groundcover or perennials and annuals that like moist, shady conditions, such as hosta, bleeding heart, azalea, impatiens, astilbe, and others.