You will need these 4 colors, 3 types of brushes (one wider and two narrowers), and a canvas.
This will be a 4 step exercise:
1. With your widest brush, take a white color and make a long horizontal line.
2. On top of this white color with the help of your middle brush create a little shorter narrower horizontal medium blue line. This should be done in a way so that you could still see the white above, below and on the right side of your medium blue.
3. With your narrowest brush, on the lower left of your white line, create a crimson line. The length of this line could be about 1/3 of the full length of the white line.
4. From the right side of the crimson line, create a figure similar to italicised letter T with a goldenrod color. As you can see from the above picture, this figure could be touching your medium blue line from below and laying on top of the white.
NOTE: Although you can see a few more colors used in this fragment, the point of this exercise was to create something interesting out of medium blue, white, crimson, and dark goldenrod. Of course, feel free to further experiment with these 4 colors if you want to expand your painting.