Cleaning and repainting the wall for amateurs

Hello, I hope I am somewhat in the right place here in the forum. I am an absolute beginner when it comes to DIY / painting. However, I would like to paint my garden wall myself. For this, I need tips and hope for your support. I have attached a picture of the wall. I would be very grateful for a step-by-step guide (also for tips on the right materials, paint, etc.). Thank you very much in advance.

I would remove a lot of verdigris with chlorine and a pressure washer.