AS far as I know, there aren’t any secrets to bleeding brakes. If there are, if someone posts them, they won’t be secrets. Make sure you have the proper type of brake fluid for your kart, i.e. Dot 3 or 4 or 5. Fill the brake bleeder tool, screw it into the master cylinder and open the valve on the tool. Put a foot long piece of clear tubing on the bleeder valve that is the highest and farthest away from the MC. Open the bleeder and drain the he fluid into a container until the air bubbles on longer appear in the clear tubing.
Close the bleeder and remove the bleeder tool and replace the cap where the bleeder was installed. Try the brake pedal. It should have a solid feeling. If not, repeat the process. Dispose the old brake fluid responsibly.
TIPS; If you have reservoirs on top of the MC, leave the caps on them. If your bleeder tool has a cap, leave it off. For front brakes, bleed the brake closest to the MC and then the farthest one.
I have bleed brakes for most Euro karts, I have never seen a bleeding nipple similar to what you see on a car, typically in the brakes I run there just screws. I wasn’t sure if using a vacuum bleeder kit would be better.