"To apply the paint" means to put or spread paint onto a surface using a brush, roller, or other tools in order to add color or a protective layer. Full definition
She quickly put aside pure forms of individual expression and started applying paint with a palette knife, creating a greater distance between herself and the painting's surface. (joseebienvenugallery.com)
In this exercise, you will see the different power and scale you can achieve by applying paint in a number of different ways and using different tools. (theguardian.com)
You will learn different ways of applying paint as well as how to give the finished look you want. (countrychicpaint.com)