Well, you just take your Visa, Mastercard
, American Express (do they even have American Express in Australia? ) to any bank and use that to get the traveler's cheques. They look similar to an actual check, but instead have set denominations on them (like cash).
There's two places where you sign the checks. Usually the top signature line you sign on all of them as soon as you get them. Then when you use them to purchase, you sign the other line at that time (as a security measure). They are usually insured in some way so that if they are lost or stolen, you can call your credit card company and have them replaced.