There are a lot of resources available at the Processing website:
I am still working on the sketched labels for the axes as a personal “fun” project.
The “process” may help you.
I took a look at tutorials, examples and started piecing together the code and learned as I progressed.
Experience comes from experience.
Your project is simple enough that you can take on this challenge.
Here is the “X” axis label that I was able to draw with my program:
