Tax adjustment help needed

Hey everybody!

Last year I had to pay some extra to the Tax authorities because I was on Married rate (the correct one) that I handled with my company, but the Tax authorities did not calculate my taxes on Married rate but on Single rate.
Long story short I received a Tax adjustment form but I am not sure what I should fill and where on the form (did not find any support document), could somebody help with this?
I attached the adjustment form and my FS3 form as well.

Thanks in advance! 🙂