How to use the brush tool?

My idea is to create some grass and flowers with using the brush tool and some wink wink to increase the space.

Step 1 : Click brush tool 

Step 2 : I choose some of the brush to create grasses, flowers and wink wink

Step 3 : I have change the color of grass become more green

Step 4 : I have use brush of flowers into the wallpaper

Step 5 : I use the wink wink brush and you can see the different between step 3 and 4