But, if you want to "make new shaders" literally... go learn how to use Heroku or Shadertoy too.
Just take someone's prior work and play around with the equations, tweaking constants or changing stuff. Go ahead and change sines into cosines... throw in a tangent here and there. Use a 'plus' instead of a 'minus', and so on.
Plus don't forget to read the OpenGL manual over at opengl.org/sdk/docs/man