Blue is a primary color and cannot be created by mixing other colors. A light blue paint is made by mixing blue with enough white to reach the desired tint. Adding blue to a light green paint will produce a green-blue tint.
Like blue, red and yellow are primary colors. Secondary colors are created by mixing two primary colors: blue and yellow make green, red and yellow make orange and red and blue make purple. Tertiary colors are made by mixing a primary color with a secondary color that has the primary color as a component. Adding white to any color creates lighter tints of the base color; adding black to any color creates darker shades of the base color. Adding gray to any color produces a less intense tone.