For the macros, I prefer to recommend to start with very straightforward macros that use `define-syntax-rule`. For example

  #lang racket
  
  (define-syntax-rule (run3times code ...)
    (begin
      (begin code ...)
      (begin code ...)
      (begin code ...)))
  
  (define x 0)
  
  (run3times
    (set! x (add1 x))
    (display x))      ; shows ==> 123

As other comment said, you have to find some good opportunity to use a simple macro.

(In this case, it is better to use the build-in `for`. Actually, `for` is defined in a macro, it is not part of the internal "secret" low level language.)

Once you are confident and you grok the difference between a macro and a function, you can try the other ways to define macros. These other ways are more flexible and can make weirder macros, and have better support when the macro is used wrongly. There are good links in the sibling comments.