You'll just need the SIM number located on the back of your SIM card to get started.  

Half Size SIM Card - Southern Phone Optus Plan

How long will activation take?

You should allow up to 48 business hours for your SIM to become active. If you’re transferring your number and have an existing SIM in your handset, wait until it stops working before inserting your new SIM.

Your SIM Number
Enter the number on the back of your SIM card without the spaces or letters. Telstra SIM numbers are 9 digits & Optus are 13 digits.