If you need to take a sample, kill some of the larger ants (the workers) away from the nest by spraying them with a household knockdown insect spray. Use a disposable plastic spoon or something similar to scoop the dead ants into a sturdy plastic container and seal. Do not add any liquid.
Place the container in a tough envelope suitable for posting, and include your name, address, telephone number and details (eg. a Mudmap) of where the ants were found with the sample.
DO NOT SEND LIVE ANTS.
Post the envelope to the:
Fire Ant Control Centre
PO Box 1241
Oxley Qld 4075