It's about 8 years that i'm programming different applications with Java, PHP etc. My sister is 11 years old and she wants to learn programming.
My question is: 'Which programming language should I recommend'.
Scratch (from MIT) is very visual, but may feel a bit "too young" for an 11-year-old.
The great thing is that they're all free to try, and you could give her a huge head start by showing her just a few short examples in any of those languages.
You can download the source code files for Teach Your Kids to Code from the No Starch book site for free, grab Python for free, and see if Python might be her first choice.
Best wishes, and let me know if I can ever be of help,