The first problem is that you think you'd make a good goal ump. All AFL goal umpires think they're awful and will never get it right, that's why they always ask for their decision to be reviewed.
You also need to sit an eye test. You don't have to pass, just sit one. If you're serious there are also junior comps everywhere where you can turn up and ask if they need a goal ump. Get feel for whether you like it and then go through all the courses. In the serious comps those goals umps are actually fairly fit and they do a fair bit of training, so it may not suit you if you prefer to sit down with a block of chocolate on a Wednesday night
There are a number of courses you can take with the view to achieving this goal. Simply get in touch with the sports governing body in S. E. QLD and they should point you in the right direction.
