Write the letter, put it in an envelope, write the address on it, take it to a Post Office. They will weigh it and tell you how much you must pay to send it.
To save money, it is a good idea to use lightweight 'airmail' paper and envelopes, but that is not vital, just a bit cheaper.
There is no age requirement but you do need to take it to the Post Office to have it weighed and have the correct stamps put on it - For Australia you have to do a customs declaration as well which is a special label put on by the post master and then signed by them
Take to Post Office and send as Airmail..They will tell you how much...
Australia is a convict colony so first it'll have to get checked for any contraband LOL!
Take it to the PO and get it weighed pay the cost of stamp...thats it
