NBA 2K11 was never released on PlayStation 2. The final NBA 2K entry on PS2 was NBA 2K10.
Your options are NBA 2K10 (which has a basic "My Player" career mode) or upgrading to a PS3/360/PC to experience the fully featured My Player mode that debuted in 2K11 with significant improvements.
Always verify platform availability before purchasing older sports titles—generation transitions often skip the outgoing console.