Welcome to the wonderful astro community!
You need to find when the Sun culminates at your location.
Use
https://www.suncalc.org/#/-31.949,11...1.30/13:31/1/0 and drag the red balloon marker thing to your site. Click the >I< button and it shows the current date and time.
Under that, it says "Culmination" and will give a time.
Go and set up a gnomon (straight up 90-degree pole) like on a sundial but using a straight pole. broom handle etc...
At the time given by suncalc for culmination, the shadow cast by your gnomon is true North to South.
Easy as that Steve!
