To Get or Check a True Friend Code, open your Friends panel and click on the 0101 button. This will open the panel below, and allow you to either Get a Code, or Check a Code. Make sure you give these codes only to people you know outside of Wizard101.
Get a code, give that code to your Friend. He needs to log in to Wizard101 within 24 hours and enter that code into the same panel, then press Check Code. If the code is typed in correctly and before it expires, you will appear on each other's Friends list. You do NOT have to both be online to become True Friends.
This will open the panel below, and allow you to either Get a Code, or Check a Code. Make sure you give these codes only to people you know outside of Wizard101.