Currently, an English Interface of Code Lyoko is available. Look for the X.A.N.A. symbol at the side, download and get ready to play! It allows you to play in Sandbox, if you just want to do whatever you want, or go to Campaign to play missions based on episodes!
Here is the website. If you have Google Chrome, it will ask you if you want to translate it to English.
The IFSCL comes with a manual, so you don't get lost. Enjoy!